kevers@chromium.org chrome-a11y-core@chromium.org Tracks when combinations of mode flags are set. Records when the accessibility mode flag changes and aligns with one of the common (named) flag bundles. Bundles that do not match a named set fall into the unnamed bucket. kevers@chromium.org chrome-a11y-core@chromium.org Tracks whether individual accessibility mode flags are set. Recorded when each mode flag is flipped from false to true. Only tracks usage within web content. aleventhal@chromium.org chrome-a11y-core@chromium.org Records how many tree updates were queued at the time updates are being processed after layout. If we are trying to process too many updates at once, we should investigate how we might be able to merge similar updates without losing important information. ikilpatrick@chromium.org layout-dev@chromium.org Time spent updating accessibility in the Blink document lifecycle. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. pdr@chromium.org paint-dev@chromium.org Time spent computing IntersectionObserver observations in the Blink document lifecycle where the observation is for gathering information about anchor elements within the visible viewport. Recorded when an intersection observation attributed to anchor element metrics is updated. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. pdr@chromium.org paint-dev@chromium.org Time spent processing main frame animations during a main frame update. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note that the histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. smcgruer@chromium.org animations-dev@chromium.org Reasons an Animation is not suitable for running on the compositor thread. Note that a given Animation may have more than one reason, so this histogram cannot be used to determine the overall rate of 'composited' vs 'noncomposited' animations. kevers@chromium.org animations-dev@chromium.org Unexpected misalignment of a phase boundary when aligned to a scroll- boundary measured in 16ths of a pixel. Recorded each time phase calculation determines the animation is in the before or after phase when a scroll- driven animation has determined that the before-active or active-after boundary is aligned to the bounds of the scroll range. sisidovski@chromium.org chikamune@chromium.org kouhei@chromium.org Records if the frame is eligible for automatic lazy-load mechanisms. This is recorded when each frame having a url in the page is created. sisidovski@google.com kouhei@chromium.org Records if the automatic lazy-load for selected performance problematic iframes is applied or not. This is recorded when each frame having a url in the page is created. See HTMLFrameOwnerElement::LazyLoadIfPossible() for more details. Note: There are two groups that lazy-load isn't applied. One group is simply the feature itself is disabled, another groupd is that feature is enabled, but there are no targeted frames on the page. lizeb@chromium.org fserb@chromium.org When a compressed hibernated 2D canvas snapshot is decompressed, duration in ms. Reported each time a canvas snapshot is decompressed. lizeb@chromium.org fserb@chromium.org When a hibernated 2D canvas snapshot is compressed, the compression ratio achieved. Reported each time a canvas snapshot is compressed. lizeb@chromium.org fserb@chromium.org When a hibernated 2D canvas snapshot is compressed, the size before compression. Reported each time a canvas snapshot is compressed. aaronhk@chromium.org junov@chromium.org Records the state of the willReadFrequently flag upon creation of a Canvas2D layer bridge, as this is the moment when it determines whether the canvas will be accelerated. fserb@chromium.org aaronhk@chromium.org Records if a Canvas is being printed as a vector or as an image. sky@chromium.org junov@chromium.org Records the effectiveness of the canvas color cache. The value is a percentage of requests for a color where the color was in the cache. For example, a value of 25% means 1 out of every 4 requests for a color was available. As this code may be called extensively, the value is logged on every 1000th request to the cache. This means the last 0-999 values are not recorded, and similarly, if the cache is accessed less than 1000 times nothing is logged. aaronhk@chromium.org fserb@chromium.org Records whether the contents in the canvas buffer needed to be preserved via a copy when replacing the target buffer for drawing a new frame. This metric is recorded each time the target buffer needs to be replaced. It's recorded once per frame. fserb@chromium.org aaronhk@chromium.org The source from which an ImageBitmap is created by a createImageBitmap call. aaronhk@chromium.org junov@chromium.org Records the state of the willReadFrequently flag during Canvas2D readback. aaronhk@chromium.org fserb@chromium.org Logs the occurrences of canvas fallback from GPU to CPU. aaronhk@chromium.org fserb@chromium.org Records if the canvas has been rendered at least once. Recorded on disposal. aaronhk@chromium.org fserb@chromium.org Records the occurrence of events related to 2D canvas GPU resource hibernation. aaronhk@chromium.org fserb@chromium.org Reports the maximum number or canvas resources used at any one time by a canvas resource provider. Logged in the destructor of CanvasResourceProvider. junov@chromium.org fserb@chromium.org Reports the maximum depth of the state stack over the lifetime of a 2d rendering context. Metric is recorded once per instance of CanvasRenderingContext2D, OffscreenRenderingContext2D, and PaintRenderingContext2D; at context destruction time. aaronhk@chromium.org fserb@chromium.org When a Document is shutdown, reports the number of canvases on that page. junov@chromium.org fserb@chromium.org Counts 2d canvas draw operations that trigger the overdraw optimization. aaronhk@chromium.org fserb@chromium.org Records the CPU, GPU and combined raster time for a random sampling of canvas frames for accelerated and deferred canvases. Records wall time for a random sampling of unaccelerated canvases. Warning: This metric may include reports from clients with low-resolution clocks (i.e. on Windows, ref. |TimeTicks::IsHighResolution()|). Such reports will cause this metric to have an abnormal distribution. When considering revising this histogram, see UMA_HISTOGRAM_CUSTOM_MICROSECONDS_TIMES for the solution. {BlinkCanvasRasterDurationType} fserb@chromium.org aaronhk@chromium.org Records the occurence of image file formats passed into toDataURL and toBlob functions in canvas. {CanvasRequestedImageMimeTypeFunctions} aaronhk@chromium.org fserb@chromium.org Logs if the canvas resource provider is accelerated or not. aaronhk@chromium.org fserb@chromium.org Records the type of resource provider used for a canvas. aaronhk@chromium.org fserb@chromium.org Records the requested resource usage for a canvas resource provider. aaronhk@chromium.org fserb@chromium.org Stores the square root of the number of pixels in a new or resized offscreen canvas. Emitted from CanvasRenderingContextHost::RecordCanvasSizeToUMA. fserb@chromium.org aaronhk@chromium.org Records the status of the idle task when finishing a toBlob call. In addition, metric values from OffscreenCanvas.convertToBlob API call are also gathered into this histogram, because the logic flow is exactly the same as canvas.toBlob. It's worth to note that the values can come from idle tasks on either main or worker thread. aaronhk@chromium.org fserb@chromium.org A new version of "Blink.Canvas.ToBlob.InitiateEncodingDelay" (which will be allowed to expire) which allows for times >10ms. This metric measures the time spent from initiating image encoding (jpeg or png) on idle task to the actual execution time of initiation, as part of a canvas.toBlob API call. This metric is useful in helping us adjust the IdleTaskStartTimeoutDelay in canvas.toBlob. When the initialization idle task is delayed for longer than IdleTaskStartTimeoutDelay, the browser will switch to a non-idle task to force initialization and encoding to occur on the main thread. In addition, metric values from OffscreenCanvas.convertToBlob API call are also gathered into this histogram, because the logic flow is exactly the same as canvas.toBlob. It's worth to note that the values can come from idle tasks on either main or worker thread. Note: This metric drops reports on clients with low-resolution clocks, which means these reports will be biased against a portion of the population on Windows. See Windows.HasHighResolutionTimeTicks for the affected sample. fserb@chromium.org aaronhk@chromium.org Time in microseconds spent on the 2D canvas toBlob API call, divided by the square root of the total number of pixels of the canvas. In addition, metric values from OffscreenCanvas.convertToBlob API call are also gathered into this histogram, because the logic flow is exactly the same as canvas.toBlob. It's worth to note that the values can come from idle tasks on either main or worker thread. Note: This metric drops reports on clients with low-resolution clocks, which means these reports will be biased against a portion of the population on Windows. See Windows.HasHighResolutionTimeTicks for the affected sample. {BlinkCanvasToBlobType} aaronhk@chromium.org fserb@chromium.org A new version of "Blink.Canvas.ToBlob.InitiateEncodingDelay" (which will be allowed to expire) which allows for times >10ms. This metric measures the total time spent on completing encoding all the rows of an image (jpeg or png), as part of a canvas.toBlob API call. Encoding occurs during one or more idle periods on the main thread and the waiting time of the next idle period is included in the measurement. If the code has swtiched to force encoding path, we will not measure the delay in this metric. This metric is useful in helping us adjust the IdleTaskCompleteTimeoutDelay in canvas.toBlob. When the encoding idle task is delayed for longer than IdleTaskCompleteTimeoutDelay, the browser will switch to a non-idle task to force encoding to happen on the main thread. In addition, metric values from OffscreenCanvas.convertToBlob API call are also gathered into this histogram, because the logic flow is exactly the same as canvas.toBlob. It's worth to note that the values can come from idle tasks on either main or worker thread. Note: This metric drops reports on clients with low-resolution clocks, which means these reports will be biased against a portion of the population on Windows. See Windows.HasHighResolutionTimeTicks for the affected sample. fserb@chromium.org aaronhk@chromium.org Time spent on 2D canvas toDataURL API call divided by the square root of the total number of pixels of the image. Smaller is faster. The idea behind this unit is that the bigger the area of a canvas the longer the operation ToDataURL takes, so we want a way to measure the overall performance regardless of the size of the canvas. Warning: This metric may include reports from clients with low-resolution clocks (i.e. on Windows, ref. |TimeTicks::IsHighResolution()|). Such reports will cause this metric to have an abnormal distribution. When considering revising this histogram, see UMA_HISTOGRAM_CUSTOM_MICROSECONDS_TIMES for the solution. {BlinkCanvasToDataURLMimeType} junov@chromium.org fserb@chromium.org aaronhk@chromium.org The reason why printing a 2D canvas failed to use vector printing. magchen@chromium.org enga@chromium.org graphics-dev@chromium.org The maximum number of total unused recyclable WebGPU resources since last clean-up. Logged in the WebGPU recyclable resouce clean-up timer function. magchen@chromium.org enga@chromium.org graphics-dev@chromium.org The maximum size of total unused recyclable WebGPU resources in KB since last clean-up. Logged in the WebGPU recyclable resouce clean-up timer function. magchen@chromium.org enga@chromium.org graphics-dev@chromium.org The number of stale recyclable WebGPU canvas resources released and logged in the WebGPU recyclable resouce clean-up timer function. brianosman@chromium.org mcasas@google.com ccameron@chromium.org Gamut properties of destination color space. brianosman@chromium.org mcasas@google.com ccameron@chromium.org Gamma properties of destination color space. brianosman@chromium.org mcasas@google.com ccameron@chromium.org The L-infinity error (in 8-bit values) of the numerical approximation of table-based ICC profile transfer functions for all channels combined, when the nonlinear approximation converged. pdr@chromium.org paint-dev@chromium.org Time spent updating and pushing layers at the end of the paint step in the Blink document lifecycle. This is implemented by PaintArtifactCompositor. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. pdr@chromium.org paint-dev@chromium.org Time spent updating compositing inputs in the Blink document lifecycle. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. lizeb@chromium.org chrome-gpu-memory@google.com Amount of memory the compositor is allowed to use. Collected once per process, on Android only. ricea@chromium.org yhirano@chromium.org Compression format passed to the constructor of the JavaScript API "CompressionStream", which is used for lossless compression of arbitrary binary data. Recorded once per call to the constructor. This measures which compression formats are most commonly used in the wild. ricea@chromium.org yhirano@chromium.org Compression format passed to the constructor of the JavaScript API "DecompressionStream", which is used for lossless decompression of arbitrary binary data. Recorded once per call to the constructor. This measures which compression formats are most commonly used in the wild. pdr@chromium.org paint-dev@chromium.org Time spent preparing the document for a canvas draw, SVG image draw or plugin during a main frame update. Includes time spent in style update and layout. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. flackr@chromium.org blink-interactions-team@google.com The depth of the discovered image node in the hit test list when performing a penetrating image selection search. Only recorded when a user long presses or right clicks a document (and an image is found). flackr@chromium.org blink-interactions-team@google.com The amount of time it took to iterate through the dom looking for an image node. Only recorded when a user long presses or right clicks a document. Note: This metric drops reports on clients with low-resolution clocks, which means these reports will be biased against a portion of the population on Windows. See Windows.HasHighResolutionTimeTicks for the affected sample. flackr@chromium.org blink-interactions-team@google.com The outcome of an image selection search that may or may not trigger the context menu. Only recorded when a user long presses or right clicks a document (and an image is found). flackr@chromium.org blink-interactions-team@google.com The outcome of a follow up retrieval of an image node after a selection has occurred, which occurs asynchronously and thus could be unsuccessful due to changes that may occur between the initial hit test and the retrieval. Only recorded when a user long presses or right clicks a document (and an image is found). gjc@chromium.org loading-dev@chromium.org blink-network-dev@chromium.org Time spent for parsing the stylesheet. Recorded when the stylesheet finishes loading and does not have cached stylesheet contents. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. gjc@chromium.org loading-dev@chromium.org blink-network-dev@chromium.org Time spent for tokenizing the stylesheet. Recorded when the response body of the stylesheet is received. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. pdr@chromium.org wangxianzhu@chromium.org paint-dev@chromium.org Time spent updating the cull rect in the Blink document lifecycle. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. wtc@google.com jzern@google.com src/third_party/blink/renderer/platform/image-decoders/avif/OWNERS The number of images per image density measured in 0.01 bits per pixel for image size in {ImageArea} megapixels. This is logged once per image load after the whole image is loaded and only for 8-bit AVIF color still images without alpha. wtc@google.com jzern@google.com src/third_party/blink/renderer/platform/image-decoders/avif/OWNERS The compressed image size in KiB per image density measured in 0.01 bits per pixel. This is logged once per image load after the whole image is loaded and only for 8-bit AVIF still images with at least 100 pixels on the smallest dimension (width or height). The reported count for a sample represents the image size rounded to the nearest KiB. wtc@google.com jzern@google.com src/third_party/blink/renderer/platform/image-decoders/OWNERS The number of images per image density measured in 0.01 bits per pixel for image size in {ImageArea} megapixels. This is logged once per image load after the whole image is loaded and only for JPEG non-grayscale images. jyrki@google.com compression-dev@google.com The compressed image size in KiB per image density measured in 0.01 bits per pixel. This is logged once per image load after the whole image is loaded and only for JPEGs with at least 100 pixels on the smallest dimension (width or height). The reported count for a sample represents the image size rounded to the nearest KiB. wtc@google.com jzern@google.com src/third_party/blink/renderer/platform/image-decoders/OWNERS The number of images per image density measured in 0.01 bits per pixel for image size in {ImageArea} megapixels. This is logged once per image load after the whole image is loaded and only for WebP lossy still images without alpha. wtc@google.com jzern@google.com src/third_party/blink/renderer/platform/image-decoders/OWNERS The compressed image size in KiB per image density measured in 0.01 bits per pixel. This is logged once per image load after the whole image is loaded and only for WebP still images with at least 100 pixels on the smallest dimension (width or height). The reported count for a sample represents the image size rounded to the nearest KiB. mcasas@chromium.org andrescj@chromium.org WebP file format parsed during Blink's header parsing phase (which should happen only once per image). urvang@chromium.org Image codec inferred during decode. The histogram is incremented when enough of the image has been downloaded to infer its width and height. Animated images are counted only once, regardless of how many frames there are. pdr@chromium.org paint-dev@chromium.org Time spent computing IntersectionObserver observations in the Blink document lifecycle where the observation is for Display Locking. Recorded when an intersection observation is made for the Display Locking reason. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. pdr@chromium.org paint-dev@chromium.org The EffectiveZoom as reported by ComputedStyle in a Blink renderer. The value is reported each time the effective zoom is set to a new value. The maximum zoom reported is 400% to keep the histogram of reasonable size. sergeyka@google.com ryankalla@google.com The latency of resolved calls to the navigator.getWebEnvironmentIntegrity() sergeyka@google.com ryankalla@google.com The results of all calls to navigator.getWebEnvironmentIntegrity() carlscab@google.com woa-performance@google Whether a GetCookiesString request for a document returned the same result as the previous one. This is an experiment to determine the usefulness of a cookie cache in the Renderer. A sample is recorded for every GetCookiesString request sent from the Document owned CookieJar. tanzachary@chromium.org web-identity-eng@google.com Records a 1 each time an accounts dialog is shown. tanzachary@chromium.org web-identity-eng@google.com Records a 1 each time a request is sent to the accounts endpoint. yigu@chromium.org web-identity-eng@google.com Records whether an IDP returns an approved clients list in the response. Records at most one sample per API call. yigu@chromium.org web-identity-eng@google.com Records the size of the approved clients list returned by IDP if applicable. Records at most one sample per API call. npm@chromium.org yigu@chromium.org web-identity-eng@google.com Records whether the FedCM auto re-authn call is blocked because the auto re-authn content settings permission is disabled. Records at most one sample per FedCM API with auto re-authn enabled: some failures could occur before this metric is recorded. npm@chromium.org yigu@chromium.org web-identity-eng@google.com Records whether the FedCM auto re-authn call is blocked because the auto re-authn is under embargo, i.e. due to cooldown. Records at most one sample per FedCM API with auto re-authn enabled: some failures could occur before this metric is recorded. npm@chromium.org web-identity-eng@google.com Records whether the FedCM auto re-authn call is blocked because preventSilentAccess() has been called on this site. Records at most one sample per FedCM API with auto re-authn enabled: some failures could occur before this metric is recorded. npm@chromium.org yigu@chromium.org web-identity-eng@google.com Records whether there was zero, one, or multiple returning accounts when a site calls the FedCM API with autoReauthn: true. Records at most one sample per failed API call: some failures could occur before this metric is recorded. npm@chromium.org yigu@chromium.org web-identity-eng@google.com Records whether auto re-authn checks succeeded or not. The count would provide roughly the number of FedCM re-authn attempts, the true count would provide the number of times the re-authn UI is shown to the user, and the false count would provide the number of attempts where auto re-authn was blocked for some non-network related reason. Records at most one sample per FedCM API with auto re-authn enabled: some failures could occur before this metric is recorded. npm@chromium.org yigu@chromium.org web-identity-eng@google.com Records the amount of time that has passed from the time the FedCM auto re-authn API was embargoed to the time in which the next call occurs. Only records a sample when there is an auto re-authn FedCM API call which is blocked due to embargo. Samples are exponentially bucketed, with a max bucket of 10 minutes, the embargo duration (see `kFederatedIdentityAutoReauthnEmbargoDuration`). pkotwicz@chromium.org web-identity-eng@google.com Records the reason that the FedCM dialog was closed (ex user clicked the dialog close button). Recorded when the FedCM dialog is closed without the user selecting an account. This includes instances where the close action is less intentional such as the virtual keyboard showing trigerring the dialog close. npm@chromium.org web-identity-eng@google.com Records the type of FedCM Android UI sheet that is being displayed when the user manually closes it. Records when the user closes this dialog, so at most once per API call that results in UI being shown. npm@chromium.org web-identity-eng@google.com Records the type of FedCM desktop UI sheet that is being displayed when the user manually closes it. Records when the user closes this dialog, so at most once per API call that results in UI being shown. yigu@chromium.org web-identity-eng@google.com Records whether the UI that a user is closing is the verify sheet or not on Android. Records at most one sample per API call. yigu@chromium.org web-identity-eng@google.com Records whether the UI that a user is closing is the verify sheet or not on desktop. Records at most one sample per API call. cbiesinger@chromium.org web-identity-eng@google.com Whenever we receive an IDP sign-in header (Google-Accounts-SignIn or IdP-SignIn-Status: action=signin) in response to a non-worker HTTP request, this records whether there was a transient user activation as indicated by ResourceRequest::has_user_gesture. tanzachary@chromium.org web-identity-eng@google.com Records the reason why the pop-up window is closed. Recorded once per opening of a pop-up window. tanzachary@chromium.org web-identity-eng@google.com Records the duration from when IdentityProvider.close() is called to when an updated accounts dialog is shown. Recorded once per IdentityProvider.close() being called given that an accounts dialog is shown. It is not recorded when the accounts dialog is never shown. tanzachary@chromium.org web-identity-eng@google.com Records the outcome of the mismatch dialog. Recorded once per the mismatch dialog being displayed. tanzachary@chromium.org web-identity-eng@google.com Records the outcome of the IDP sign-in pop-up window. Recorded once per pop-up window triggered by the user. tanzachary@chromium.org web-identity-eng@google.com Records the outcome of attempting to show a pop-up window, triggered by the user clicking on the "Continue" button on the IDP sign-in status mismatch dialog. Recorded once per click of the "Continue" button. cbiesinger@chromium.org web-identity-eng@google.com Whenever we receive an IDP sign-in header (Google-Accounts-SignOut or IdP-SignIn-Status: action=signout) in response to a non-worker HTTP request, this records whether there was a transient user activation as indicated by ResourceRequest::has_user_gesture. tanzachary@chromium.org web-identity-eng@google.com Records whether the FedCM request is made before or after the start of the window onload event. Records once per API call when the FedCmMultipleIdentityProviders flag is disabled. yigu@chromium.org web-identity-eng@google.com Records whether the user selected account is for sign-in or not. Records at most one sample per API call. npm@chromium.org web-identity-eng@google.com Records the number of accounts the match a login hint. Records at the time the accounts received by the FedCM API are filtered. tanzachary@chromium.org web-identity-eng@google.com Records a 1 each time a mismatch dialog is shown. tanzachary@chromium.org web-identity-eng@google.com Records the number of navigator.credentials.get() requests made in a document. Requests made when FedCM is disabled, when there is a pending FedCM request or for the purpose of MDocs or multi-IDP are not counted. Records at most one sample for every document where at least one navigator.credentials.get() request is made. No samples are recorded if the count is 0. The bucketing method used is base::UmaHistogramCounts100. npm@chromium.org web-identity-eng@google.com Records the type of frame that invokes preventSilentAccess(). Records only when there is an existing FedCM sharing permission on the main frame, and some frame in the page invokes the preventSilentAccess() JavaScript call. Possible values are: main frame, same-site iframe, and cross-site iframe, where the site of the iframe is compared with the site of the main frame. npm@chromium.org web-identity-eng@google.com Records the RP Context used in a FedCM call. Records only when the RP Context flag is enabled. npm@chromium.org web-identity-eng@google.com Records the NetError from the accounts list endpoint. This histogram is only recorded when the IDP Sign-In Status of an IDP is marked as signout as a result of the accounts list endpoint not returning any accounts. pkotwicz@chromium.org web-identity-eng@google.com Recorded each time that the privacy-policy link in the FedCM prompt is clicked. pkotwicz@chromium.org web-identity-eng@google.com Recorded each time that the terms-of-service link in the FedCM prompt is clicked. yigu@chromium.org web-identity-eng@google.com Records the reason why there is no valid account in the response. Recorded at most once per accounts fetch when the response is received. cbiesinger@chromium.org web-identity-eng@google.com Records the result of CSP checks in the FedCM API. pkotwicz@chromium.org web-identity-eng@google.com Records whether the browser's knowledge of whether the user is signed-in to the IDP based on observing signin/signout HTTP headers matches the information returned by the accounts endpoint. Recorded at most once per navigator.credentials.get() call after sending the request to the accounts endpoint. npm@chromium.org web-identity-eng@google.com Records the mediation requirement of a request token call to the FedCM API. Records a sample when the FedCM call is completed, i.e. at the same time as Blink.FedCm.Status.RequestIdToken. yigu@chromium.org web-identity-eng@google.com Records the status of a request token call to the FedCM API. Revoke is deprecated. Removed in June 2022. yigu@chromium.org web-identity-eng@google.com Records the status of a revoke call to the FedCM API. tanzachary@chromium.org web-identity-eng@google.com Records whether user sign-in states between IDP and browser match. Records a sample after browser receives an account list from IDP prior to showing UI. tanzachary@chromium.org web-identity-eng@google.com Records the duration from when an accounts dialog is shown to when dialog is destroyed e.g. user selects an account, user closes the dialog, or the developer aborts the request. This duration includes the time when the accounts dialog is inactive e.g. user switches to a different tab. Samples are at most 10 minutes. Records a sample when an accounts dialog which is not the verifying UI for auto re-authentication is shown. In a previous definition, Blink.FedCm.Timing.AccountsDialogShownDuration, a sample was recorded when an accounts dialog (including the verifying UI) is shown. yigu@chromium.org web-identity-eng@google.com Records the time from when the accounts dialog is shown to when the user explicitly closes the dialog without selecting any account. Only records a sample when the user sees and *explicitly* closes the dialog. For instance, the accounts dialog being closed as a result of the user focusing a different part of the browser UI does not count as explicitly closing the dialog. yigu@chromium.org web-identity-eng@google.com Records the time from when the accounts dialog is shown to when the user presses the Continue button. Only records a sample when the user sees and taps the "Continue" button on the dialog. yigu@chromium.org web-identity-eng@google.com Records the time from when the user presses the Continue button to when the token response is received. Only records a sample when the token response is received. tanzachary@chromium.org web-identity-eng@google.com Records the duration from when a mismatch dialog is shown to when user triggers IDP sign-in pop-up window or when dialog is destroyed e.g. user closes the dialog. This duration includes the time when the mismatch dialog is inactive e.g. user switches to a different tab. Samples are at most 10 minutes. Records a sample when a mismatch dialog is shown. tanzachary@chromium.org web-identity-eng@google.com Records the duration from when RequestToken is called directly in navigator.credentials.get to when RequestToken would be called if invoked through a posted task. Records once per API call when the FedCmMultipleIdentityProviders flag is disabled and RequestToken is called during or after the window onload event. If RequestToken is called before the window onload event, Blink.FedCm.Timing.WindowOnloadDelayDuration is recorded instead. yigu@chromium.org web-identity-eng@google.com Records the time from when a call to the API was made to when the accounts dialog is shown. Only records a sample when the dialog is shown. yigu@chromium.org web-identity-eng@google.com Records the overall time from when the API is called to when the token response is received. Only records a sample when the token response is received. tanzachary@chromium.org web-identity-eng@google.com Records the duration from when RequestToken is called directly in navigator.credentials.get to when RequestToken would be called if invoked through a window onload event listener. Records once per API call when the FedCmMultipleIdentityProviders flag is disabled and RequestToken is called prior to the start of the window onload event. If RequestToken is called during or after the window onload event, Blink.FedCm.Timing.PostTaskDelayDuration is recorded instead. npm@chromium.org web-identity-eng@google.com Records the number of accounts returned by a getUserInfo() call. Records once per request with a successful accounts fetch. Records when the request is completed. npm@chromium.org web-identity-eng@google.com Records the status of a getUserInfo() call. Records once per request when the request is completed, right before running the callback. npm@chromium.org web-identity-eng@google.com Records the time from when a getUserInfo() call is received on the browser process to the time it is completed. Records once per request with a successful accounts fetch. Records when the request is completed. yigu@chromium.org web-identity-eng@google.com Records whether the WebContents is visible when the browser is ready to show the accounts dialog to the user. Records at most one sample per API call. shivanisha@chromium.org dom@chromium.org lbrady@google.com Records creation and navigation outcomes for a fenced frame. This is written either when a fenced frame navigates successfully, or when some issue causes either the creation or navigation of a fenced frame to stop. shivanisha@chromium.org dom@chromium.org lbrady@google.com If a fenced frame failed to load due to incorrectly set sandbox flags, records whether or not the fenced frame was attempting to be created in a top-level frame. This is written whenever a fenced frame creation fails due to sandbox flags not being permissive enough. shivanisha@chromium.org dom@chromium.org lbrady@google.com Records if a fenced frame's size is set after the size had been frozen. The size of a fenced frame is frozen once it navigates to a page, and results in the inner contents being scaled to fit the new dimensions without telling it the frame's new size. This is only logged up to one time throughout a fenced frame's life, and will not be logged if the size is never set after being frozen. shivanisha@chromium.org dom@chromium.org lbrady@google.com Records whether an opaque-ads fenced frame's size was changed because the provided size was not in the list of allowed sizes. This will not log anything for a default mode fenced frame. This will log when an opaque-ads fenced frame has its size frozen (which is triggered when it navigates to its first page). shivanisha@chromium.org dom@chromium.org lbrady@google.com If a fenced frame failed to load due to incorrectly set sandbox flags, records which sandbox flags that should be unsandboxed ended up being sandboxed, causing the load to fail. This is written whenever a fenced frame creation fails due to sandbox flags not being permissive enough. If multiple sandbox flags are incorrectly set, it will log every sandbox flag that was not set correctly for each failed load. mych@chromium.org bfcache-dev@chromium.org The total microseconds spent between the calls to ResourceFetcher::ClearContext and ResourceFetcher::RemoveResourceLoader, roughly stands for how long a fetch keepalive request stays after the environment (document/context) is gone, including both success and failure. The duration is recorded within ResourceFetcher::RemoveResourceLoader when the fetcher is already detached. mych@chromium.org bfcache-dev@chromium.org Records true when loading a fetch keepalive request succeeds after ResourceFetcher is detached; Records false if the load fails. mych@chromium.org bfcache-dev@chromium.org Records true when an attempt is made to prepare to load a fetch keepalive request. mych@chromium.org bfcache-dev@chromium.org Records true when a successful attempt is made to load a fetch keepalive request; Records false if the load fails. Note that the sum of the two buckets may still be smaller than Blink.Fetch.KeepAlive.Total, as the requests that were early-terminated due to quota exceeded may not be logged here. cduvall@chromium.org csharrison@chromium.org The total microseconds spent in ResourceFetcher::requestResource for {Scheme}. This histogram only records metrics on machines with high-resolution clocks. cduvall@chromium.org jam@chromium.org Measures the time it takes to fetch queued subresource preloads for a document in a {FrameType}. Logged every time preloads need to be fetched after the {IsInitial} preload scan. gjc@chromium.org blink-network-dev@chromium.org Time spent for decoding the fonts. Recorded when a font resource creates its decoded data. This histogram is only logged in platforms with high-resolution clocks. drott@chromium.org layout-dev@chromium.org Percentage of emoji clusters of all emoji clusters going through shaping calls that are shaped as either .notdef/tofu glyphs or are shapes as more than one glyph, which usually indicates that an emoji sequence was not shaped correctly due to the emoji font not supporting it. Recorded per page/worker and on page unload if the page contained emoji. drott@chromium.org layout-dev@chromium.org Tracks adoption ratio of variable fonts compared to conventional (in the sense of non-variable) web fonts. Recorded at the time of instantiating a Skia SkTypeface from the successfully decoded web font blob. pdr@chromium.org paint-dev@chromium.org Time spent computing layouts due to Javascript value requests. Specifically, time spent in Blink Document::UpdateStyleAndLayout. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. carlosk@chromium.org harringtond@chromium.org feed@chromium.org Android only: The time spent by the renderer main thread to collect and send back to the browser process a web page's canonical link. This is recorded every time the renderer fulfills a request for this information. This histogram is only logged in platforms with high-resolution clocks. pdr@chromium.org paint-dev@chromium.org Time spent processing rAF-aligned input during a main frame update. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. pdr@chromium.org paint-dev@chromium.org Time spent preparing the document for hit testing during a main frame update. It does not compute the actual hit test time, rather the style, layout, compositing, etc time to prepare for the test. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. sky@chromium.org tebbi@chromium.org dom-dev@chromium.org Number of bytes after which the html fast-path parser aborted. This does not count the bytes the fast-path parser did not look at. We measure this since aborting the fast-path and falling back to the normal parser is wasted effort. This is recorded after every invocation of Element::setInnerHTML. sky@chromium.org tebbi@chromium.org dom-dev@chromium.org The amount of time the innerHTML fast-path parser took before reaching input it could not handle. This is recorded when Element::setInnerHTML is called, and at the moment when the input it can't handle is reached. This histogram does not record metrics on machines with low-resolution clocks. sky@chromium.org tebbi@chromium.org dom-dev@chromium.org Captures the result of the innerHTML fast-path parser. This is recorded every time Element::setInnerHTML is called and only if the innerHTML fast-path parser is enabled. sky@chromium.org tebbi@chromium.org dom-dev@chromium.org Number of bytes successfully parsed by the innerHTML fast-path parser. This is recorded if the innerHTML fast-path parser completes successfully and is logged at the end of parsing the content supplied to Element::setInnerHTML. sky@chromium.org tebbi@chromium.org dom-dev@chromium.org The time it takes for the innerHTML fast-path parser to complete processing text from Element::setInnerHTML. This is recorded if fast-path innerHTML is enabled, and completes successfully. This histogram does not record metrics on machines with low-resolution clocks. sky@chromium.org tebbi@chromium.org dom-dev@chromium.org The total time it takes to complete parsing of Element::setInnerHTML. This includes the time taken by the fast-path parser (even if it failed). This is recorded after every invocation of Element::setInnerHTML. This histogram does not record metrics on machines with low-resolution clocks. sky@chromium.org tebbi@chromium.org dom-dev@chromium.org This is logged if the innerHTML fast-path parser fails because an {Type} tag is encountered. This value is an aggregate (bitmask) that identifies which {Type} groupings were encountered. Ideally a single bitmask would be logged, but the dashboard doesn't deal well with large bitmasks. The individual groupings are recorded via one of Blink.HTMLFastPathParser.*.Mask0-3 (* is one of UnsupportedContextTag or UnsupportedTag). sky@chromium.org tebbi@chromium.org dom-dev@chromium.org See description of Blink.HTMLFastPathParser.*.CompositeMask for an overview of this including when it is logged. The value is a bitmask that identifies which tags were encountered: {MaskBit} masonf@chromium.org dom-dev@chromium.org The number of chunks parsed while loading a page. Each chunk represents a piece of the HTML content that can be loaded without blocking or yielding. This is only reported for http/https urls. This histogram does not record metrics on machines with low-resolution clocks. masonf@chromium.org dom-dev@chromium.org The number of characters processed while parsing a document during page load. This is computed as the sum of all the characters appended to the input string sequence for the parser. This is only reported for http/https urls. This histogram does not record metrics on machines with low-resolution clocks. masonf@chromium.org dom-dev@chromium.org While parsing a page, the maximum time used to parse a single chunk before being blocked, yielding or completing, in microseconds. This does not include time spent executing script. This is only reported for http/https urls. This histogram does not record metrics on machines with low-resolution clocks. masonf@chromium.org dom-dev@chromium.org While parsing a page, the minimum time used to parse a single chunk before being blocked, yielding or completing, in microseconds. This does not include time spent executing script. This is only reported for http/https urls. This histogram does not record metrics on machines with low-resolution clocks. masonf@chromium.org dom-dev@chromium.org While parsing a page, the total amount of time spent in the HTMLDocumentParser performing parsing, in microseconds. This does not include time spent executing script. This is only reported for http/https urls. This histogram does not record metrics on machines with low-resolution clocks. sky@chromium.org dom-dev@chromium.org The time between when the first content has been received by the HTMLDocumentParser and when parsing begins. This is effectively measuring the time between when SchedulePumpTokenizer() is called, and when the task runs that does the parsing. This is only reported for http/https urls. This histogram does not record metrics on machines with low-resolution clocks. masonf@chromium.org dom-dev@chromium.org While parsing a page, the average number of tokens parsed across all chunks. This is only reported for http/https urls. This histogram does not record metrics on machines with low-resolution clocks. masonf@chromium.org dom-dev@chromium.org While parsing a page, the maximum number of tokens parsed as a chunk. This is only reported for http/https urls. This histogram does not record metrics on machines with low-resolution clocks. masonf@chromium.org dom-dev@chromium.org While parsing a page, the minimum number of tokens parsed as a chunk. This is only reported for http/https urls. This histogram does not record metrics on machines with low-resolution clocks. masonf@chromium.org dom-dev@chromium.org While parsing a page, the total number of tokens parsed across all chunks. This is only reported for http/https urls. This histogram does not record metrics on machines with low-resolution clocks. masonf@chromium.org dom-dev@chromium.org While parsing a page, the average time between parsing of two chunks, in microseconds. Will not be recorded if only one chunk was parsed. This is only reported for http/https urls. This histogram does not record metrics on machines with low-resolution clocks. masonf@chromium.org dom-dev@chromium.org While parsing a page, the maximum time between parsing of two chunks, in microseconds. Will not be recorded if only one chunk was parsed. This is only reported for http/https urls. This histogram does not record metrics on machines with low-resolution clocks. masonf@chromium.org dom-dev@chromium.org While parsing a page, the minimum time between parsing of two chunks, in microseconds. Will not be recorded if only one chunk was parsed. This is only reported for http/https urls. This histogram does not record metrics on machines with low-resolution clocks. wtc@google.com jzern@google.com src/third_party/blink/renderer/platform/image-decoders/avif/OWNERS If an AVIF image has a clean aperture ('clap') property, record what kind of clean aperture it is when one frame of the image is decoded fully. The histogram is intended to check whether clean aperture properties with a nonzero origin are common. vmpstr@chromium.org khushalsagar@chromium.org This histogram records whether an image has been decoded by a single client or by multiple clients during decoding. For an image to be decoded, it is always requested by a client with a client_id. If an image has been requested by multiple clients, it would be decoded more than once. The histogram value is recorded at most two times per image (once per bucket). There will be overlap for two buckets, but we can get the the number of an image decodeded by only one client with the difference between two buckets. This helps us to know how often images get duplicated decoding in real life. andrescj@chromium.org chromeos-gfx@google.com For JPEG and WebP images, whether all image data has been received before decoding begins or whether we are still receiving data and will need to send partial image data to the decoder and pause/resume decoding until complete. It is emitted when the DeferredImageDecoder is about to create the first DecodingImageGenerator for an image. andrescj@chromium.org src/third_party/blink/renderer/platform/image-decoders/OWNERS Number of pixels in a decoded JPEG image. Recorded after decoding is done by Blink's JPEG decoder (as opposed to, possibly, a hardware decode accelerator). Tracking the image area may include degenerate cases, e.g., an image with area = 10000 and dimensions = 1x10000. However, it is reasonable to assume these cases are relatively rare and the area of the image can serve as a proxy of how useful a decode accelerator can be (the larger the area, the better). andrescj@chromium.org mcasas@chromium.org JPEG color space of a decoded image as guessed by libjpeg_turbo. Recorded after decoding is done by Blink's JPEG decoder (as opposed to, possibly, a hardware decode accelerator). When the color space is YCbCr, the chroma subsampling is also recorded. pdr@chromium.org paint-dev@chromium.org Time spent updating layers in the compositor thread during a ProxyMain::BeginMainFrame. It is the actual work time, excluding time spent waiting for the compositor thread to begin. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. Cursor Control feature is launched, the metrics is no longer needed. Removed in March 2022. ctzsm@chromium.org changwan@chromium.org input-dev@chromium.org Records if a GestureScrollBegin is for cursor control. wangxianzhu@chromium.org paint-dev@chromium.org Reports LocalFrameView::min_scroll_delta_to_update_intersection_.x() after an intersection observation update. The frequency is the same as Blink.UpdateViewportIntersection.UpdateTime. wangxianzhu@chromium.org paint-dev@chromium.org Reports IntersectionGeometry::min_scroll_delta_to_update_.x() after an intersection observation update. The frequency is number of geometry observers per frame times the frequency of Blink.UpdateViewportIntersection.UpdateTime. wangxianzhu@chromium.org paint-dev@chromium.org Reports LocalFrameView::min_scroll_delta_to_update_intersection_.y() after an intersection observation update. The frequency is the same as Blink.UpdateViewportIntersection.UpdateTime. wangxianzhu@chromium.org paint-dev@chromium.org Reports IntersectionGeometry::min_scroll_delta_to_update_.y() after an intersection observation update. The frequency is the same as Blink.IntersectionObservation.MinScrollDeltaToUpdateY. wangxianzhu@chromium.org paint-dev@chromium.org Reports LocalFrameView::IntersectionObservationState after a scroll. This is reported on each scroll of any scroller. pdr@chromium.org paint-dev@chromium.org Time spent computing IntersectionObserver observations in the Blink document lifecycle. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. wangxianzhu@chromium.org paint-dev@chromium.org Reports if an intersection observer update uses cached rects. The frequency is the same as Blink.IntersectionObservation.MinScrollDeltaToUpdateY. szager@chromium.org paint-dev@chromium.org Number of IntersectionObserver computations for blink-internal consumers that were performed during the course of a single main frame. szager@chromium.org paint-dev@chromium.org Number of IntersectionObserver computations for javascript consumers that were performed during the course of a single main frame. pdr@chromium.org paint-dev@chromium.org Time spent preparing the document to answer a Javascript API query or request. Examples include scrool offset requests, queries of layout dimensions, SVG path queries, etc. Includes time spent in style update and layout, or via EnsurePaintLocationDataValidForNode. Some of these calls may be servicing internal needs, but we have no way to disambiguate those from JS driven activity. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. pdr@chromium.org paint-dev@chromium.org Time spent computing IntersectionObserver observations in the Blink document lifecycle where the observation is due to a Javascript request. Recorded when an intersection observation is made for the Javascript reason. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. joedow@chromium.org garykac@chromium.org Records each call to the navigator.keyboard{Lock|Unlock} methods. tkent@chromium.org layout-dev@chromium.org Time spent to clone physical fragments, recorded during LayoutOverflow computation. tkent@chromium.org layout-dev@chromium.org Time spent to rebuild container physical fragments, recorded on sub-tree root layout. pdr@chromium.org ikilpatrick@chromium.org layout-dev@chromium.org Time spent in PaintLayer::UpdateLayerPositionsAfterLayout. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. pdr@chromium.org layout-dev@chromium.org Time spent updating layout in the Blink document lifecycle. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. pdr@chromium.org paint-dev@chromium.org Total network response size for each lazy loaded image that has loaded. This is recorded at the point that the image element completes loading. This includes all entries in `Blink.LazyLoadedImageBeforeDocumentOnLoad.Size` as well as lazy loaded images that load after document load. pdr@chromium.org paint-dev@chromium.org Total network response size for each lazy loaded image that has loaded before the document has finished loading. This is recorded at the point that the image element completes loading. pdr@chromium.org paint-dev@chromium.org Time spent computing IntersectionObserver observations in the Blink document lifecycle where the observation is due to a Lazy Image Loading request. Recorded when an intersection observation is made to determine when a lazy loaded image should be loaded. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. kouhei@chromium.org src/third_party/blink/renderer/core/lcp_critical_path_predictor/OWNERS Measures the size of the identified LCP element locator in bytes. The metric is emitted before the element locator is serialized to the LCP Critical Path Predictor (LCPP) database, so it can inform us if the current ElementLocator encoding scheme is reasonable in terms of its output size. alexnj@chromium.org src/third_party/blink/renderer/core/lcp_critical_path_predictor/OWNERS Measures the number of resources identified to be influencing the load of the LCP element. The metric is emitted before the influencer list is serialized to the LCP Critical Path Predictor (LCPP) database. alexnj@chromium.org src/third_party/blink/renderer/core/lcp_critical_path_predictor/OWNERS Measures the size of the longest URL influencing the load of the LCP element. The metric is emitted before the influencer list is serialized to the LCP Critical Path Predictor (LCPP) database. alexnj@chromium.org src/third_party/blink/renderer/core/lcp_critical_path_predictor/OWNERS Counts the number of URLs matched during a subsequent page load, from the set of URLs identified to be influencing the load of the LCP element. The metric is emitted as LCP Critical Path Predictor calculates dependencies of the current LCP candidate. alexnj@chromium.org src/third_party/blink/renderer/core/lcp_critical_path_predictor/OWNERS Measures the percent of matched LCP influencer URLs against the predicted set of URLs. The metric is emitted as LCP Critical Path Predictor calculates dependencies of the current LCP candidate. kouhei@chromium.org src/third_party/blink/renderer/core/lcp_critical_path_predictor/OWNERS Measures the number of resources that got priority boost from LCPP signals for page loads with non-empty LCPP hint data. This metric is emitted for every page load when it is about to emit "onload" event. The metric would tell us how much LCP Critical Path Predictor (LCPP), is affecting page load in the wild. yhirano@chromium.org loadingg-dev@chromium.org The amount of time taken to get a cached response. Recorded when the response arrives, and recorded only when both of the response and the code cache were cached. yhirano@chromium.org loading-dev@chromium.org The amount of time taken to get a code cache. Recorded when the response arrives, and recorded only when both of the response and the code cache were cached. pdr@chromium.org paint-dev@chromium.org Reports if a local frame root ever receives a FirstContentfulPaint signal. Only recorded for local frame roots that run at least one main frame update. pdr@chromium.org paint-dev@chromium.org Reports if the main frame ever receives a FirstContentfulPaint signal. Only recorded for main frame local frame roots that run at least one main frame update. pdr@chromium.org paint-dev@chromium.org Time between a BeginMainFrame and paint results commit in Blink. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. pdr@chromium.org paint-dev@chromium.org Time spent computing IntersectionObserver observations in the Blink document lifecycle where the observation is for a media element. Recorded when an intersection observation is made attributed to a media element (such as video auto-play). Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. gjc@chromium.org blink-network-dev@chromium.org Type of cached non-static resources reused across Documents when loading a new document in the same renderer. Recorded by the ResourceFetcher when a resource is requested for a new document and is not static. If the resource is available from the memory cache and previously loaded by a different document, the resource will be considered as reused. Repetitive requests to the same url in a document will be counted only once. Warning: an unexpected reorder happened in Apr 2021 (https://crrev.com/c/2798954). Please do not trust older reports. gjc@chromium.org blink-network-stack@chromium.org Size of the resource strong references saved to the memory cache. Recorded when the user navigates to a newpage under the same origin. Recorded only with feature flag MemoryCacheStrongReference. bashi@chromium.org blink-network-dev@chromium.org Records whether a cached response exists in another renderer that has the same process isolation policies. Recorded when ResourceFetcher fetches a resource from network. This histogram is for `{Destination}` destination. bashi@chromium.org blink-network-dev@chromium.org Records the time between when a renderer receives an IPC to look for cached response and when another renderer receives the response of that IPC. The IPC is sent when ResourceFetcher fetches a resource from network. Recorded when the renderer receives the response. Note: This histogram is not recorded on low-resolution clock clients. bashi@chromium.org blink-network-dev@chromium.org Records the time between when a renderer sends an IPC to look for cached response and when another renderer receives that IPC. The IPC is sent when ResourceFetcher fetches a resource from network. Recorded when the renderer receives the response. Note: This histogram is not recorded on low-resolution clock clients. hiroshige@chromium.org lizeb@chromium.org gjc@chromium.org loading-dev@chromium.org RevalidationPolicy used for non-preloading requests of async and defer scripts. https://crbug.com/1043679 https://crbug.com/1376866 Warning: this histogram was expired from 2021/10/25 to 2022/12/09; data may be missing. hiroshige@chromium.org gjc@chromium.org loading-dev@chromium.org RevalidationPolicy used for requests that hit Resource only referenced from MemoryCache for each resource type ({ResourceType}). https://crbug.com/579496 Requests counted by this are also counted by Blink.MemoryCache.RevalidationPolicy or Blink.MemoryCache.RevalidationPolicy.Preload. https://crbug.com/1376866 Warning: this histogram was expired from 2021-04-21 to 2022-12-09; data may be missing. This histogram's {ResourceType} was broken until 2023-03-09; data before the date may not be stored. hiroshige@chromium.org gjc@chromium.org loading-dev@chromium.org RevalidationPolicy used for preloading requests for each resource type ({ResourceType}). https://crbug.com/579496 https://crbug.com/1376866 Warning: this histogram was expired from 2021-04-21 to 2022-12-09; data may be missing. This histogram's {ResourceType} was broken until 2023-03-09; data before the date may not be stored. hiroshige@chromium.org gjc@chromium.org loading-dev@chromium.org RevalidationPolicy used for non-preloading requests for each resource type. https://crbug.com/579496 https://crbug.com/1376866 Warning: this histogram was expired from 2021-04-21 to 2022-12-09; data may be missing. This histogram's {ResourceType} was broken until 2023-03-09; data before the date may not be stored. kumagi@google.com gaul@google.com paint-dev@google.com Whether element extraction phase succeed without consuming entire 4ms time budget in MobileFriendlinessChecker::ComputeBadTapTargetsRatio() evaluation. This metric recorded at 5 seconds after first MainFrame's commit and periodically every 1 minutes after that. kumagi@google.com gaul@google.com paint-dev@google.com The time taken in MobileFriendliness::ComputebadTapTargetsRatio evalution. This metric recorded at 5 seconds after first MainFrame's commit and periodically every 1 minutes after that. The histogram does not record metric on machines with low-resolution clocks. cduvall@chromium.org jam@chromium.org The time taken to query the notification permission status. This is recorded each time a sync call is made. aaronhk@chromium.org fserb@chromium.org Records the creation of a new offscreen canvas in OffscreenCanvas::Create. aaronhk@chromium.org fserb@chromium.org Stores the square root of the number of pixels in a new or resized offscreen canvas. Emitted from CanvasRenderingContextHost::RecordCanvasSizeToUMA. aaronhk@chromium.org fserb@chromium.org Records a call to transfer a canvas offscreen. aaronhk@chromium.org fserb@chromium.org Records when an offscreen canvas has been transferred from the main thread to a worker. khushalsagar@chromium.org vmpstr@chromium.org Computes the area of img, video or canvas elements which is painted outside the content rect if 'overflow' property is respected on these elements. pdr@chromium.org paint-dev@chromium.org Time spent updating paint in the Blink document lifecycle. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. cduvall@chromium.org jam@chromium.org Time spent parsing style sheets for a document. Only recorded when the CSSParserContext has a document available. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. cduvall@chromium.org jam@chromium.org Measures the time it takes to update the plugin list. This can happen, for example, during Navigator.plugins.get. jbroman@chromium.org Categorizes MIME types of responses to "prefetch" links. Intended to gather data about whether this feature is used mainly for documents, subresources, or both. Emitted once per resource fetched (which may be more than one per page). cduvall@chromium.org swarm-team@google.com Measures the time from the creation of a PreloadRequest to when PreloadRequest::Start is called. Logged for each PreloadRequest::Start call. pdr@chromium.org paint-dev@chromium.org Time spent updating paint properties and paint invalidation in the Blink document lifecycle. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. cduvall@chromium.org jam@chromium.org Measures the time from when a resource request completes to when the renderer is notified. Logged for every resource request. cduvall@chromium.org jam@chromium.org Measures the time from when a redirect from a resource request happens to when the renderer is notified. Logged for every resource request redirect. cduvall@chromium.org jam@chromium.org Measures the time from when a response from a resource request is started to when the renderer is notified. Logged for every resource request. cduvall@chromium.org jam@chromium.org Measures the time from when the renderer starts a resource request to when it is actually started on the network. Logged for every resource request. sullivan@chromium.org mmocny@chromium.org speed-metrics-dev@chromium.org The duration of a single user interaction: https://web.dev/better-responsiveness-metric/#group-events-into-interactions This metric is emitted once for every interaction in the web contents {InteractionType} cduvall@chromium.org jam@chromium.org Measures the time it takes to scan and preload subresources for a document in a {FrameType}. Logged every time the {IsInitial} preload scan is performed. haraken@chromium.org Duration of time taken to scan pending activities of all V8 wrappers in a worker thread. dom@chromium.org chrome-loading@google.com The total number of async scripts associated with a document at the time parsing has finished. chikamune@chromium.org hiroshige@chromium.org sisidovski@chromium.org Number of synchronous scripts that were deferred for a mainframe by the ForceDeferScriptIntervention. This includes both inline scripts and external scripts that had their execution deferred until after parsing completes. Recorded at the end of parsing when ForceDeferScriptIntervention is enabled. chikamune@chromium.org hiroshige@chromium.org sisidovski@chromium.org Number of external synchronous scripts that were deferred for a mainframe by the ForceDeferScriptIntervention. Recorded at the end of parsing when ForceDeferScriptIntervention is enabled. chikamune@chromium.org hiroshige@chromium.org sisidovski@chromium.org Number of synchronous scripts that were deferred for a subframe by the ForceDeferScriptIntervention. This includes both inline scripts and external scripts that had their execution deferred until after parsing completes. Recorded at the end of parsing when ForceDeferScriptIntervention is enabled. chikamune@chromium.org hiroshige@chromium.org sisidovski@chromium.org Number of external synchronous scripts that were deferred for a subframe by the ForceDeferScriptIntervention. Recorded at the end of parsing when ForceDeferScriptIntervention is enabled. kouhei@chromium.org hiroshige@chromium.org chikamune@chromium.org Number of script elements for each scheduling type, recorded when each script loading reaches the #prepare-a-script state defined in the spec, with http or https request. Warning: this histogram was expired from 2018-12-31 to 2022-05-25; data may be missing. cduvall@chromium.org jam@google.com The time spent generating the source text for a script resource. Logged when the source text is accessed for the first time. Emitted at most once per script resource. Note that clients without high-resolution clocks will report 0 for very short times. pdr@chromium.org paint-dev@chromium.org Time spent preparing the document to service browser driven behaviors. Examples include accessibility, intersection observer, display locking and spell checking. Includes time spent in style update and layout. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. yigu@chromium.org web-identity-eng@google.com Records how often the verification backend is unavailable for the WebOTP API and the corresponding reason. This is recorded once per OTP request. yigu@chromium.org web-identity-eng@google.com SmsFetcher subscribes to incoming SMSes with origins from SmsProvider. This metric records the number of pending origins that are not unsubscribed when the SmsFetcher subscribes to new origins. yigu@chromium.org web-identity-eng@google.com Records the reason why using the WebOTP API on desktop failed on the sharing path. It records one sample per invocation of the API. yigu@chromium.org goto@chromium.org web-identity-eng@google.com Records how many times the infobar was called and how many times the infobar replaced a keyboard. yigu@chromium.org goto@chromium.org web-identity-eng@google.com Records the result of a call to the WebOTP API. yigu@chromium.org web-identity-eng@google.com Records the status of parsing an incoming SMS when using the WebOTP API. It records one sample per incoming SMS. Note: This metric does not cover cross-devices WebOTP. yigu@chromium.org goto@chromium.org web-identity-eng@google.com Records the duration from when the API is called to when the request is cancelled by the service due to duplicated requests or lack of delegate. yigu@chromium.org goto@chromium.org web-identity-eng@google.com Records the duration from when the keyboard was replaced with an infobar until when the user clicked the cancel button. yigu@chromium.org goto@chromium.org web-identity-eng@google.com Records the time from when a successful SMS was retrieved to when the user presses the Cancel button. yigu@chromium.org goto@chromium.org web-identity-eng@google.com Records the time from when a successful SMS was retrieved to when the user presses the Continue button. yigu@chromium.org goto@chromium.org web-identity-eng@google.com Records the duration from when the API is called to when an SMS has been successfully received. yigu@chromium.org goto@chromium.org web-identity-eng@google.com Records the duration from when the API is called to when the user successfully receives the SMS and presses continue to pass the incoming SMS to the site and proceed with the SMS verification flow. yigu@chromium.org goto@chromium.org web-identity-eng@google.com Records the duration from when the API is called to when the user successfully receives the SMS and presses "Deny" to terminate the SMS verification flow. yigu@chromium.org web-identity-eng@google.com Records whether the web contents that receives the OTP is visible or not for the UserConsent backend. Recorded at most once per API call when Chrome sees the OTP from the expected origin. jbroman@chromium.org src/third_party/blink/renderer/core/speculation_rules/OWNERS The amount of time between when a fetch of speculation rules is started and when it is finished. Recorded each time such a fetch occurs. jbroman@chromium.org src/third_party/blink/renderer/core/speculation_rules/OWNERS Outcome of an attempt to load a speculation rule set. Recorded once per attempt, whether triggered by a response header, by the parser or by script. pdr@chromium.org layout-dev@chromium.org Time spent updating style in the Blink document lifecycle. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. pdr@chromium.org paint-dev@chromium.org Time spent updating a SVG image once all data is received. This histogram does not record metrics on machines with low-resolution clocks. pdr@chromium.org paint-dev@chromium.org Time spent computing geometry information about iframes from the perspective of their embedding document. This time is also included in the Blink.IntersectionObservation.UpdateTime metric. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. chasej@chromium.org feature-control@chromium.org Records usage of animated CSS properties used on a page, either statically or dynamically, from the time the page is initialised to when it is closed or navigated away from. Each property is counted at most once per page per view via PageLoadMetricsObserver. This histogram counts CSS properties only when they are animated by a CSS Animation. Refer to Blink.UseCounter.CSSProperties for more details. As of M69, Blink.UseCounter.AnimatedCSSProperties is moved from the blink side to the browser side. Not recorded if the page is prerendered and cancelled. chasej@chromium.org feature-control@chromium.org Records usage of CSS properties used on a page, either statically or dynamically, from the time the page is initialised to when it is closed or navigated away from. Each property is counted at most once per page per view via PageLoadMetricsObserver. The first time a CSS property is parsed on a page, the histogram is updated to increment the counter. Each histogram bucket corresponds to a CSS property (eg. width, border-radius). The exception is the 'Total pages measured' bucket - this counts the number of pages that CSS properties were counted on. When a page navigation occurs the page count bucket is incremented and tracking of the set of which properties have been seen is reset. These numbers give the percentage of pages that use a CSS property. For example, if the 'border-radius' histogram bucket has a count of 250, and the page count bucket (i.e. bucket number 1) has a count of 1000 - this means that 1000 pages were recorded, and border-radius was used on 25% of those pages. Note that CSS properties used inside of SVG images are tracked separately in the Blink.UseCounter.SVGImage.CSSProperties histogram. As of M57 this histogram supercedes WebCore.FeatureObserver.CSSProperties. As of M69, Blink.UseCounter.AnimatedCSSProperties is moved from the blink side to the browser side. Not recorded if the page is prerendered and cancelled. iclelland@chromium.org feature-control@chromium.org Counts enforced DocumentPolicyViolationReport generated in a document. iclelland@chromium.org feature-control@chromium.org Counts the use of a specific document policy via the "Document-Policy" HTTP response header. iclelland@chromium.org feature-control@chromium.org Counts the use of a specific document policy via the "policy" attribute. Each policy is counted only once per page load. Not recorded if the page is prerendered and cancelled. iclelland@chromium.org feature-control@chromium.org Counts report only DocumentPolicyViolationReport generated in a document. chasej@chromium.org feature-control@chromium.org Count of how many page loads use various features for pages with a chrome-extension:// URL only. The PageVisits bucket is incremented for each page load, and the other buckets incremented at most once per PageVisit via the WebCore::UserCounter class. Warning: This histogram represents pre-renderer metrics and so is flawed under OOPIF. Warning: this histogram was expired from 2021-10-10 to 2022-07-12; data may be missing. iclelland@chromium.org feature-control@chromium.org Counts the use of a specific feature policy via the "Feature-Policy" HTTP response header. chasej@chromium.org feature-control@chromium.org Count of how many page loads use various features across all frames in a page. The PageVisits bucket is incremented for each page load, and the other buckets incremented at most once per PageVisit via blink::UseCounter and UseCounterPageLoadMetricsObserver. Note that this histogram only counts page with HTTP/HTTPS URL scheme. Feature used in pages with other URL schemes might be counted in other histograms: "extension://" : Blink.UseCounter.Extensions.Features "file://" : Blink.UseCounter.File.Features Not recorded if the page is prerendered and cancelled. toyoshim@chromium.org mparc-dev@chromium.org Similar to Blink.UseCounter.AnimatedCSSProperties, this records usage of animated CSS properties used on a FencedFrame Page. Either statically or dynamically, from the time the page is initialised to when it is closed or navigated away from. Each property is counted at most once per page per view via PageLoadMetricsObserver. This histogram counts CSS properties only when they are animated by a CSS Animation. Refer to Blink.UseCounter.FencedFrames.CSSProperties for more details. Not recorded if the page is prerendered and cancelled. toyoshim@chromium.org mparc-dev@chromium.org Similar to Blink.UseCounter.CSSProperties, this records usage of CSS properties used on a FencedFrame Page. Either statically or dynamically, from the time the page is initialised to when it is closed or navigated away from. Each property is counted at most once per page per view via PageLoadMetricsObserver. The first time a CSS property is parsed on a page, the histogram is updated to increment the counter. Each histogram bucket corresponds to a CSS property (eg. width, border-radius). The exception is the 'Total pages measured' bucket - this counts the number of pages that CSS properties were counted on. When a page navigation occurs the page count bucket is incremented and tracking of the set of which properties have been seen is reset. These numbers give the percentage of pages that use a CSS property. For example, if the 'border-radius' histogram bucket has a count of 250, and the page count bucket (i.e. bucket number 1) has a count of 1000 - this means that 1000 pages were recorded, and border-radius was used on 25% of those pages. Note that CSS properties used inside of SVG images are not tracked. Not recorded if the page is prerendered and cancelled. toyoshim@chromium.org mparc-dev@chromium.org Similar to Blink.UseCounter.Features, this counts how many page loads use various features across all frames in a FencedFrame page. The PageVisits bucket is incremented for each page load, and the other buckets incremented at most once per PageVisit via blink::UseCounter and UseCounterPageLoadMetricsObserver. Note that this histogram only counts FencedFrames page with HTTP/HTTPS URL scheme. Feature used in pages with other URL schemes are not counted. Not recorded if the page is prerendered and cancelled. toyoshim@chromium.org mparc-dev@chromium.org Similar to Blink.UseCounter.MainFrame.Features, this counts how many page loads use various features across in the main frame of a FencedFrame page. The PageVisits bucket is incremented at the beginning of each page load and the other buckets incremented at most once per PageVisit via blink::UseCounter and UseCounterPageLoadMetricsObserver throughout the lifetime of a page load metrics observer. This histogram counts usage of web features in FencedFrames' main frame only. Refer to Blink.UseCounter.FencedFrames.Features for more details. Not recorded if the page is prerendered and cancelled. lbrady@google.com shivanisha@chromium.org dom@chromium.org Similar to Blink.UseCounter.PermissionsPolicy.Allow2, this counts the use of a specific permissions policy feature via the "allow" attribute on iframes under FencedFrames root. Each policy is counted only once per page load. But the page is limited only to FencedFrames pages. Not recorded if the page is prerendered and cancelled. lbrady@google.com shivanisha@chromium.org dom@chromium.org Similar to Blink.UseCounter.PermissionsPolicy.Header2, this counts the use of a specific permissions policy feature via both "Feature-Policy" and "Permissions-Policy" HTTP response header. Each policy is counted only once per page load. But the page is limited only to FencedFrames pages. Not recorded if the page is prerendered and cancelled. lbrady@google.com shivanisha@chromium.org dom@chromium.org Similar to Blink.UseCounter.PermissionsPolicy.Violation.Enforce, this counts the actual enforced permissions policy violation. The metrics is triggered when ExecutionContext::IsFeatureEnabled with ReportOptions::ReportOnFailure as param returns false, at most once per page visit. But the page is limited only to FencedFrames pages. Not recorded if the page is prerendered and cancelled. yhirano@chromium.org mkwst@chromium.org Count of how many `file:` URL page loads use various features across all frames in the page. This histogram has the same semantics as "Blink.UseCounter.Features", but applies only to `file:` URLs (which that histogram does not include). Refer to "Blink.UseCounter.Features" for more details. This counter expired on 2021-01-28 and was re-enabled on 2022-12-19. chasej@chromium.org feature-control@chromium.org Count of how many page loads use various features across in the main frame of a page. The PageVisits bucket is incremented at the beginning of each page load and the other buckets incremented at most once per PageVisit via blink::UseCounter and UseCounterPageLoadMetricsObserver throughout the lifetime of a page load metrics observer. This histogram counts usage of web features in main frame only. Refer to Blink.UseCounter.Features for more details. Not recorded if the page is prerendered and cancelled. iclelland@chromium.org feature-control@chromium.org Counts the use of a specific permissions policy feature via the "allow" attribute on iframes. Each policy is counted only once per page load. Version 2 fixes the mismatched histogram name with data collected. Not recorded if the page is prerendered and cancelled. iclelland@chromium.org feature-control@chromium.org Counts the use of a specific permissions policy feature via both "Feature-Policy" and "Permissions-Policy" HTTP response header. Each policy is counted only once per page load. Version 2 fixes the mismatched histogram name with data collected. Not recorded if the page is prerendered and cancelled. iclelland@chromium.org feature-control@chromium.org Counts the actual enforced permissions policy violation. The metrics is triggered when ExecutionContext::IsFeatureEnabled with ReportOptions::ReportOnFailure as param returns false, at most once per page visit. Not recorded if the page is prerendered and cancelled. pdr@chromium.org paint-dev@chromium.org Time spent preparing the document to service user driven behaviors. Examples include inspector, selection, editing, find-in-page and focus. Includes time spent in style update and layout. Note: As of 04/2023, scroll updates are included in user driven behaviors. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. pdr@chromium.org paint-dev@chromium.org Records the effective connection type whenever a lazily loaded image that was initially above the fold becomes visible before it finishes loading. pdr@chromium.org paint-dev@chromium.org Records the effective connection type whenever a lazily loaded image that was initially below the fold becomes visible before it finishes loading. pdr@chromium.org paint-dev@chromium.org Milliseconds spent waiting for a lazily loaded image to load. 0ms is recorded if the image is already loaded by the time it is visible. See also the AboveTheFold3 and BelowTheFold3 versions of this metric. pdr@chromium.org paint-dev@chromium.org Milliseconds spent waiting for an initially above-the-fold lazily loaded image to load. 0ms is recorded if the image is already loaded by the time it is visible. EffectiveConnectionType (2G, 3G, etc) is recorded as suffix to this histogram. View the base histogram to see results aggregated across all connection types. {BlinkVisibleLoadTimeSuffixes} pdr@chromium.org paint-dev@chromium.org Milliseconds spent waiting for an initially below-the-fold lazily loaded image to load. 0ms is recorded if the image is already loaded by the it is visible. EffectiveConnectionType (2G, 3G, etc) is recorded as suffix to this histogram. View the base histogram to see results aggregated across all connection types. {BlinkVisibleLoadTimeSuffixes} szager@chromium.org paint-dev@chromium.org Elapsed time between when a widget first registers a state invalidation that requires a visual refresh; and when the main thread begins a main frame that will send the updated visual state to the compositor. This histogram only records metrics on machines with high-resolution clocks. pdr@chromium.org paint-dev@chromium.org Time spent waiting for the compositor thread to begin processing a layer update inside ProxyMain::BeginMainFrame. Note: PreFCP metrics will be recorded even if FCP is not reached, whereas AggregatedPreFCP metrics are only recorded if FCP is reached. Note: Not recorded on ~5% of Windows machines with low-resolution clocks. Note: The histograms with PreFCP/PostFCP/AggregatedPreFCP suffixes before 105.0.5175.0 were impacted by https://crbug.com/1330675. Be careful when aggregating or comparing these histograms across the version. dalecurtis@chromium.org media-dev-uma@chromium.org Whether a given JavaScript ImageDecoder instance completed operation successfully or not. Logged upon destruction of the instance. dalecurtis@chromium.org media-dev-uma@chromium.org Image codec provided to JavaScript ImageDecoder constructor. Logged once per successful construction upon completion of construction. dalecurtis@chromium.org media-dev-uma@chromium.org The codec type used with {AudioCodecApi}. Recorded for every successful configure() call. dalecurtis@chromium.org media-dev-uma@chromium.org The final media::StatusCode for each {CodecApi} instance. The final status code is either StatusCode::kOk or the first fatal error encountered. Recorded once upon destruction for each codec type. dalecurtis@chromium.org media-dev-uma@chromium.org The codec type used with {VideoCodecApi}. Recorded for every successful configure() call. cduvall@chromium.org jam@chromium.org Measures the time it takes to perform a {CookieOperation} operation from the CookieJar. Logged on every operation from the CookieJar. junov@chromium.org fserb@chromium.org aaronhk@chromium.org Time spent executing a script task that draws content to a {Context} context of a {Host}. Note: This metric drops reports on clients with low-resolution clocks, which means these reports will be biased against a portion of the population on Windows. See Windows.HasHighResolutionTimeTicks for the affected sample. junov@chromium.org fserb@chromium.org aaronhk@chromium.org Memory usage on the {Heap} heap in KB, sampled after the execution of script tasks that render content to a {Host}, using a {Context} context.