blob: c8778e9360fc3c18e2156d82e2861b5191ccf9e6 [file] [log] [blame]
// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/public/common/features.h"
#include "base/feature_list.h"
#include "build/build_config.h"
#include "build/chromeos_buildflags.h"
#include "services/network/public/cpp/features.h"
#include "third_party/blink/public/common/forcedark/forcedark_switches.h"
namespace blink {
namespace features {
// Enable intervention for download that was initiated from or occurred in an ad
// frame without user activation.
const base::Feature kBlockingDownloadsInAdFrameWithoutUserActivation{
const base::Feature kCOLRV1Fonts{"COLRV1Fonts",
// Enable CSS Container Queries. Also implies LayoutNGGrid and CSSContainSize1D.
const base::Feature kCSSContainerQueries{"CSSContainerQueries",
// Controls whether the Conversion Measurement API infrastructure is enabled.
const base::Feature kConversionMeasurement{"ConversionMeasurement",
const base::Feature kGMSCoreEmoji{"GMSCoreEmoji",
// Whether the HandwritingRecognition API can be enabled by origin trial.
// Disabling this feature disables both the origin trial and the mojo interface.
const base::Feature kHandwritingRecognitionWebPlatformApiFinch{
// Enable defer commits to avoid flash of unstyled content, for same origin
// navigation only.
const base::Feature kPaintHolding{"PaintHolding",
// Enable defer commits to avoid flash of unstyled content, for all navigation.
const base::Feature kPaintHoldingCrossOrigin{"PaintHoldingCrossOrigin",
// Enable eagerly setting up a CacheStorage interface pointer and
// passing it to service workers on startup as an optimization.
// TODO(crbug/1077916): Re-enable once the issue with COOP/COEP is fixed.
const base::Feature kEagerCacheStorageSetupForServiceWorkers{
// Controls script streaming.
const base::Feature kScriptStreaming{"ScriptStreaming",
// Allow streaming small (<30kB) scripts.
const base::Feature kSmallScriptStreaming{"SmallScriptStreaming",
// Enables user level memory pressure signal generation on Android.
const base::Feature kUserLevelMemoryPressureSignal{
"UserLevelMemoryPressureSignal", base::FEATURE_DISABLED_BY_DEFAULT};
// Perform memory purges after freezing only if all pages are frozen.
const base::Feature kFreezePurgeMemoryAllPagesFrozen{
"FreezePurgeMemoryAllPagesFrozen", base::FEATURE_DISABLED_BY_DEFAULT};
// Freezes the user-agent as part of
const base::Feature kFreezeUserAgent{"FreezeUserAgent",
// Enables the frequency capping for detecting overlay popups. Overlay-popups
// are the interstitials that pop up and block the main content of the page.
const base::Feature kFrequencyCappingForOverlayPopupDetection{
// Enables the frequency capping for detecting large sticky ads.
// Large-sticky-ads are those ads that stick to the bottom of the page
// regardless of a user’s efforts to scroll, and take up more than 30% of the
// screen’s real estate.
const base::Feature kFrequencyCappingForLargeStickyAdDetection{
// Enable Display Locking JavaScript APIs.
const base::Feature kDisplayLocking{"DisplayLocking",
const base::Feature kJSONModules{"JSONModules",
const base::Feature kForceSynchronousHTMLParsing{
"ForceSynchronousHTMLParsing", base::FEATURE_DISABLED_BY_DEFAULT};
// Enables top-level await in modules.
const base::Feature kTopLevelAwait{"TopLevelAwait",
// Enable EditingNG by default. This feature is for a kill switch.
const base::Feature kEditingNG{"EditingNG", base::FEATURE_ENABLED_BY_DEFAULT};
// Enable LayoutNG.
const base::Feature kLayoutNG{"LayoutNG", base::FEATURE_ENABLED_BY_DEFAULT};
// Enable TableNG
const base::Feature kLayoutNGTable{"LayoutNGTable",
const base::Feature kMixedContentAutoupgrade{"AutoupgradeMixedContent",
// Used to control the collection of anchor element metrics (
// If kNavigationPredictor is enabled, then metrics of anchor elements
// in the first viewport after the page load and the metrics of the clicked
// anchor element will be extracted and recorded. Additionally, navigation
// predictor may preconnect/prefetch to resources/origins to make the
// future navigations faster.
const base::Feature kNavigationPredictor {
#if defined(OS_ANDROID)
// This feature returns empty arrays for navigator.plugins and
// navigator.mimeTypes. It is disabled for now, due to compat issues.
const base::Feature kNavigatorPluginsEmpty{"NavigatorPluginsEmpty",
// Enable browser-initiated dedicated worker script loading
// (PlzDedicatedWorker).
const base::Feature kPlzDedicatedWorker{"PlzDedicatedWorker",
// Enable Portals.
// Note that default enabling this does not expose the portal
// element on its own, but does allow its use with an origin trial. This was the
// case for the M85 Android only origin trial (
const base::Feature kPortals {
#if defined(OS_ANDROID)
// When kPortals is enabled, allow portals to load content that is third-party
// (cross-origin) to the hosting page. Otherwise has no effect.
const base::Feature kPortalsCrossOrigin{"PortalsCrossOrigin",
// Enable the <fencedframe> element; see Note that enabling
// this feature does not automatically expose this element to the web, it only
// allows the element to be enabled by the runtime enabled feature, for origin
// trials.
const base::Feature kFencedFrames{"FencedFrames",
const base::FeatureParam<FencedFramesImplementationType>::Option
fenced_frame_implementation_types[] = {
{FencedFramesImplementationType::kShadowDOM, "shadow_dom"},
{FencedFramesImplementationType::kMPArch, "mparch"}};
const base::FeatureParam<FencedFramesImplementationType>
&kFencedFrames, "implementation_type",
// Enable the prerender2.
// Note that default enabling this does not enable the Prerender2 features
// because kSetOnlyIfOverridden is used for setting WebRuntimeFeatures'
// Prerender2. To enable this feature, we need to force-enable this feature
// using chrome://flags/#enable-prerender2 or --enable-features=Prerender2
// command line or a valid Origin Trial token in the page.
const base::Feature kPrerender2 {
#if defined(OS_ANDROID)
bool IsPrerender2Enabled() {
return base::FeatureList::IsEnabled(blink::features::kPrerender2);
// Enable limiting previews loading hints to specific resource types.
const base::Feature kPreviewsResourceLoadingHintsSpecificResourceTypes{
// Perform a memory purge after a renderer is backgrounded. Formerly labelled as
// the "PurgeAndSuspend" experiment.
// TODO( Disabled by default on Android for historical
// reasons. Consider enabling by default if experiment results are positive.
const base::Feature kPurgeRendererMemoryWhenBackgrounded {
#if defined(OS_ANDROID)
// Enables Raw Clipboard.
const base::Feature kRawClipboard{"RawClipboard",
// Kill switch for getCurrentBrowsingContextMedia(), which allows capturing of
// web content from the tab from which it is called. (
const base::Feature kRTCGetCurrentBrowsingContextMedia{
"RTCGetCurrentBrowsingContextMedia", base::FEATURE_ENABLED_BY_DEFAULT};
// Changes the default RTCPeerConnection constructor behavior to use Unified
// Plan as the SDP semantics. When the feature is enabled, Unified Plan is used
// unless the default is overridden (by passing {sdpSemantics:'plan-b'} as the
// argument). This was shipped in M72.
// The feature is still used by virtual test suites exercising Plan B.
const base::Feature kRTCUnifiedPlanByDefault{"RTCUnifiedPlanByDefault",
// Prevents throwing an exception when the RTCPeerConnection is constructed with
// {sdpSemantics:"plan-b"} and the Deprecation Trial is not enabled. May be used
// as a kill-switch if necessary.
const base::Feature kRTCAllowPlanBOutsideDeprecationTrial{
"RTCAllowPlanBOutsideDeprecationTrial", base::FEATURE_ENABLED_BY_DEFAULT};
// Determines if the SDP attrbute extmap-allow-mixed should be offered by
// default or not. The default value can be overridden by passing
// {offerExtmapAllowMixed:false} as an argument to the RTCPeerConnection
// constructor.
const base::Feature kRTCOfferExtmapAllowMixed{"RTCOfferExtmapAllowMixed",
// Enables waiting for codec support status notification from GPU factory in RTC
// codec factories.
const base::Feature kRTCGpuCodecSupportWaiter{"kRTCGpuCodecSupportWaiter",
const base::FeatureParam<int> kRTCGpuCodecSupportWaiterTimeoutParam{
&kRTCGpuCodecSupportWaiter, "timeout_ms", 3000};
// Prevents workers from sending IsolateInBackgroundNotification to V8
// and thus instructs V8 to favor performance over memory on workers.
const base::Feature kV8OptimizeWorkersForPerformance{
"V8OptimizeWorkersForPerformance", base::FEATURE_ENABLED_BY_DEFAULT};
// Controls whether the implementation of the performance.measureMemory
// web API uses PerformanceManager or not.
const base::Feature kWebMeasureMemoryViaPerformanceManager{
"WebMeasureMemoryViaPerformanceManager", base::FEATURE_ENABLED_BY_DEFAULT};
// Enables negotiation of experimental multiplex codec in SDP.
const base::Feature kWebRtcMultiplexCodec{"WebRTC-MultiplexCodec",
// Causes WebRTC to replace host ICE candidate IP addresses with generated
// names ending in ".local" and resolve them using mDNS.
const base::Feature kWebRtcHideLocalIpsWithMdns{
"WebRtcHideLocalIpsWithMdns", base::FEATURE_ENABLED_BY_DEFAULT};
// Causes WebRTC to not set the color space of video frames on the receive side
// in case it's unspecified. Otherwise we will guess that the color space is
// BT709.
const base::Feature kWebRtcIgnoreUnspecifiedColorSpace{
"WebRtcIgnoreUnspecifiedColorSpace", base::FEATURE_DISABLED_BY_DEFAULT};
// When enabled, wake ups from throttleable TaskQueues are limited to 1 per
// minute in a page that has been backgrounded for 5 minutes.
// Intensive wake up throttling is enforced in addition to other throttling
// mechanisms:
// - 1 wake up per second in a background page or hidden cross-origin frame
// - 1% CPU time in a page that has been backgrounded for 10 seconds
// Feature tracking bug:
// The base::Feature should not be read from; rather the provided accessors
// should be used, which also take into account the managed policy override of
// the feature.
// The base::Feature is enabled by default on all platforms. However, on
// Android, it has no effect because page freezing kicks in at the same time. It
// would have an effect if the grace period ("grace_period_seconds" param) was
// reduced.
const base::Feature kIntensiveWakeUpThrottling{
"IntensiveWakeUpThrottling", base::FEATURE_ENABLED_BY_DEFAULT};
// Name of the parameter that controls the grace period during which there is no
// intensive wake up throttling after a page is hidden. Defined here to allow
// access from The FeatureParam is defined in
// third_party/blink/renderer/platform/scheduler/common/
const char kIntensiveWakeUpThrottling_GracePeriodSeconds_Name[] =
// Run-time feature for the |rtc_use_h264| encoder/decoder.
const base::Feature kWebRtcH264WithOpenH264FFmpeg{
"WebRTC-H264WithOpenH264FFmpeg", base::FEATURE_ENABLED_BY_DEFAULT};
// Experiment of the delay from navigation to starting an update of a service
// worker's script.
const base::Feature kServiceWorkerUpdateDelay{
"ServiceWorkerUpdateDelay", base::FEATURE_DISABLED_BY_DEFAULT};
// Enable the use of Speculation Rules in access the private prefetch proxy
// (chrome/browser/prefetch/prefetch_proxy/).
const base::Feature kSpeculationRulesPrefetchProxy{
"SpeculationRulesPrefetchProxy", base::FEATURE_DISABLED_BY_DEFAULT};
// Freeze scheduler task queues in background after allowed grace time.
// "stop" is a legacy name.
const base::Feature kStopInBackground {
#if defined(OS_ANDROID)
// Freeze scheduler task queues in background on network idle.
// This feature only works if stop-in-background is enabled.
const base::Feature kFreezeBackgroundTabOnNetworkIdle{
"freeze-background-tab-on-network-idle", base::FEATURE_DISABLED_BY_DEFAULT};
// Enable the Storage Access API.
const base::Feature kStorageAccessAPI{"StorageAccessAPI",
// Enable text snippets in URL fragments.
const base::Feature kTextFragmentAnchor{"TextFragmentAnchor",
// File handling integration.
const base::Feature kFileHandlingAPI{"FileHandlingAPI",
// Allows for synchronous XHR requests during page dismissal
const base::Feature kAllowSyncXHRInPageDismissal{
"AllowSyncXHRInPageDismissal", base::FEATURE_DISABLED_BY_DEFAULT};
// Font enumeration and data access.
const base::Feature kFontAccess{"FontAccess",
// Font enumeration and data access.
const base::Feature kFontAccessPersistent{"FontAccessPersistent",
// Kill switch for the Compute Pressure API.
const base::Feature kComputePressure{"ComputePressure",
// Prefetch request properties are updated to be privacy-preserving. See
const base::Feature kPrefetchPrivacyChanges{"PrefetchPrivacyChanges",
// Decodes jpeg 4:2:0 formatted images to YUV instead of RGBX and stores in this
// format in the image decode cache. See for details on the
// feature.
const base::Feature kDecodeJpeg420ImagesToYUV{"DecodeJpeg420ImagesToYUV",
// Decodes lossy WebP images to YUV instead of RGBX and stores in this format
// in the image decode cache. See for details on the feature.
const base::Feature kDecodeLossyWebPImagesToYUV{
"DecodeLossyWebPImagesToYUV", base::FEATURE_ENABLED_BY_DEFAULT};
// Enables cache-aware WebFonts loading. See
// The feature is disabled on Android for WebView API issue discussed at
const base::Feature kWebFontsCacheAwareTimeoutAdaption {
#if defined(OS_ANDROID)
// Enabled to block programmatic focus in subframes when not triggered by user
// activation (see htpps://
const base::Feature kBlockingFocusWithoutUserActivation{
"BlockingFocusWithoutUserActivation", base::FEATURE_DISABLED_BY_DEFAULT};
// A server-side switch for the REALTIME_AUDIO thread priority of
// RealtimeAudioWorkletThread object. When disabled, it will use the NORMAL
// priority thread.
const base::Feature kAudioWorkletThreadRealtimePriority{
"AudioWorkletThreadRealtimePriority", base::FEATURE_DISABLED_BY_DEFAULT};
// A feature to reduce the set of resources fetched by No-State Prefetch.
const base::Feature kLightweightNoStatePrefetch {
#if defined(OS_ANDROID)
// Automatically convert light-themed pages to use a Blink-generated dark theme
const base::Feature kForceWebContentsDarkMode{
"WebContentsForceDark", base::FEATURE_DISABLED_BY_DEFAULT};
// A feature to enable using the smallest image specified within image srcset
// for users with Save Data enabled.
const base::Feature kSaveDataImgSrcset{"SaveDataImgSrcset",
// Which algorithm should be used for color inversion?
const base::FeatureParam<ForceDarkInversionMethod>::Option
forcedark_inversion_method_options[] = {
{ForceDarkInversionMethod::kHslBased, "hsl_based"},
{ForceDarkInversionMethod::kCielabBased, "cielab_based"},
{ForceDarkInversionMethod::kRgbBased, "rgb_based"}};
const base::FeatureParam<ForceDarkInversionMethod>
// Should images be inverted?
const base::FeatureParam<ForceDarkImageBehavior>::Option
forcedark_image_behavior_options[] = {
{ForceDarkImageBehavior::kInvertNone, "none"},
{ForceDarkImageBehavior::kInvertSelectively, "selective"}};
const base::FeatureParam<ForceDarkImageBehavior> kForceDarkImageBehaviorParam{
&kForceWebContentsDarkMode, "image_behavior",
// Do not invert text lighter than this.
// Range: 0 (do not invert any text) to 256 (invert all text)
// Can also set to -1 to let Blink's internal settings control the value
const base::FeatureParam<int> kForceDarkTextLightnessThresholdParam{
&kForceWebContentsDarkMode, "text_lightness_threshold", -1};
// Do not invert backgrounds darker than this.
// Range: 0 (invert all backgrounds) to 256 (invert no backgrounds)
// Can also set to -1 to let Blink's internal settings control the value
const base::FeatureParam<int> kForceDarkBackgroundLightnessThresholdParam{
&kForceWebContentsDarkMode, "background_lightness_threshold", -1};
const base::FeatureParam<ForceDarkIncreaseTextContrast>::Option
forcedark_increase_text_contrast_options[] = {
{ForceDarkIncreaseTextContrast::kFalse, "false"},
{ForceDarkIncreaseTextContrast::kTrue, "true"}};
// Should text contrast be increased.
const base::FeatureParam<ForceDarkIncreaseTextContrast>
&kForceWebContentsDarkMode, "increase_text_contrast",
// Instructs WebRTC to honor the Min/Max Video Encode Accelerator dimensions.
const base::Feature kWebRtcUseMinMaxVEADimensions {
// TODO( enable other platforms.
// Blink garbage collection.
// Enables compaction of backing stores on Blink's heap.
const base::Feature kBlinkHeapCompaction{"BlinkHeapCompaction",
// Enables concurrently marking Blink's heap.
const base::Feature kBlinkHeapConcurrentMarking{
"BlinkHeapConcurrentMarking", base::FEATURE_ENABLED_BY_DEFAULT};
// Enables concurrently sweeping Blink's heap.
const base::Feature kBlinkHeapConcurrentSweeping{
"BlinkHeapConcurrentSweeping", base::FEATURE_ENABLED_BY_DEFAULT};
// Enables incrementally marking Blink's heap.
const base::Feature kBlinkHeapIncrementalMarking{
"BlinkHeapIncrementalMarking", base::FEATURE_ENABLED_BY_DEFAULT};
// Enables a marking stress mode that schedules more garbage collections and
// also adds additional verification passes.
const base::Feature kBlinkHeapIncrementalMarkingStress{
"BlinkHeapIncrementalMarkingStress", base::FEATURE_DISABLED_BY_DEFAULT};
// Enables removing AppCache delays when triggering requests when the HTML was
// not fetched from AppCache.
const base::Feature kVerifyHTMLFetchedFromAppCacheBeforeDelay{
// Controls whether we use ThreadPriority::DISPLAY for renderer
// compositor & IO threads.
const base::Feature kBlinkCompositorUseDisplayThreadPriority {
#if defined(OS_ANDROID) || BUILDFLAG(IS_CHROMEOS_ASH) || defined(OS_WIN)
// Ignores cross origin windows in the named property interceptor of Window.
const base::Feature kIgnoreCrossOriginWindowWhenNamedAccessOnWindow{
// Enables redirecting subresources in the page to better compressed and
// optimized versions to provide data savings.
const base::Feature kSubresourceRedirect{"SubresourceRedirect",
// Enables redirecting src videos in the page to better compressed and optimized
// versions to provide data savings.
const base::Feature kSubresourceRedirectSrcVideo{
"SubresourceRedirectSrcVideo", base::FEATURE_DISABLED_BY_DEFAULT};
// When enabled, enforces new interoperable semantics for 3D transforms.
// See
const base::Feature kTransformInterop{"TransformInterop",
const base::Feature kBackfaceVisibilityInterop{
"BackfaceVisibilityInterop", base::FEATURE_DISABLED_BY_DEFAULT};
// When enabled, beacons (and friends) have ResourceLoadPriority::kLow,
// not ResourceLoadPriority::kVeryLow.
const base::Feature kSetLowPriorityForBeacon{"SetLowPriorityForBeacon",
// When enabled allows the header name used in the blink
// CacheStorageCodeCacheHint runtime feature to be modified. This runtime
// feature disables generating full code cache for responses stored in
// cache_storage during a service worker install event. The runtime feature
// must be enabled via the blink runtime feature mechanism, however.
const base::Feature kCacheStorageCodeCacheHintHeader{
"CacheStorageCodeCacheHintHeader", base::FEATURE_DISABLED_BY_DEFAULT};
const base::FeatureParam<std::string> kCacheStorageCodeCacheHintHeaderName{
&kCacheStorageCodeCacheHintHeader, "name", "x-CacheStorageCodeCacheHint"};
// When enabled, the beforeunload handler is dispatched when a frame is frozen.
// This allows the browser to know whether discarding the frame could result in
// lost user data, at the cost of extra CPU usage. The feature will be removed
// once we have determine whether the CPU cost is acceptable.
const base::Feature kDispatchBeforeUnloadOnFreeze{
"DispatchBeforeUnloadOnFreeze", base::FEATURE_ENABLED_BY_DEFAULT};
// Enables the use of GpuMemoryBuffer images for low latency 2d canvas.
// TODO(khushalsagar): Enable this if we're using SurfaceControl and GMBs allow
// us to overlay these resources.
const base::Feature kLowLatencyCanvas2dImageChromium {
#endif // OS_CHROMEOS
// Enables the use of shared image swap chains for low latency 2d canvas.
const base::Feature kLowLatencyCanvas2dSwapChain{
"LowLatencyCanvas2dSwapChain", base::FEATURE_ENABLED_BY_DEFAULT};
// Enables the use of shared image swap chains for low latency webgl canvas.
const base::Feature kLowLatencyWebGLSwapChain{"LowLatencyWebGLSwapChain",
// Enables Dawn-accelerated 2D canvas.
const base::Feature kDawn2dCanvas{"Dawn2dCanvas",
// Enables small accelerated canvases for webview (
const base::Feature kWebviewAccelerateSmallCanvases{
"WebviewAccelerateSmallCanvases", base::FEATURE_DISABLED_BY_DEFAULT};
// When enabled, frees up CachedMetadata after consumption by script resources
// and modules. Needed for the experiment in
const base::Feature kDiscardCodeCacheAfterFirstUse{
"DiscardCodeCacheAfterFirstUse", base::FEATURE_DISABLED_BY_DEFAULT};
// Kill switch for the new element.offsetParent behavior.
// TODO( Remove this once the feature has
// landed and no compat issues are reported.
const base::Feature kOffsetParentNewSpecBehavior{
"OffsetParentNewSpecBehavior", base::FEATURE_DISABLED_BY_DEFAULT};
// Slightly delays rendering if there are fonts being preloaded, so that
// they don't miss the first paint if they can be loaded fast enough (e.g.,
// from the disk cache)
const base::Feature kFontPreloadingDelaysRendering{
"FontPreloadingDelaysRendering", base::FEATURE_ENABLED_BY_DEFAULT};
// 50ms is the overall best performing value in our experiments.
const base::FeatureParam<int> kFontPreloadingDelaysRenderingParam{
&kFontPreloadingDelaysRendering, "delay-in-ms", 50};
const base::Feature kKeepScriptResourceAlive{"KeepScriptResourceAlive",
const base::Feature kDelayAsyncScriptExecution{
"DelayAsyncScriptExecution", base::FEATURE_DISABLED_BY_DEFAULT};
const base::FeatureParam<DelayAsyncScriptDelayType>::Option
delay_async_script_execution_delay_types[] = {
{DelayAsyncScriptDelayType::kFinishedParsing, "finished_parsing"},
const base::FeatureParam<DelayAsyncScriptDelayType>
&kDelayAsyncScriptExecution, "delay_type",
// Feature and parameters for delaying low priority requests behind "important"
// (either high or medium priority requests). There are two parameters
// highlighted below.
const base::Feature kDelayCompetingLowPriorityRequests{
"DelayCompetingLowPriorityRequests", base::FEATURE_DISABLED_BY_DEFAULT};
// The delay type: We don't want to delay low priority requests behind
// "important" requests forever. Rather, it makes sense to have this behavior up
// *until* some relevant loading milestone, which this parameter specifies.
const base::FeatureParam<DelayCompetingLowPriorityRequestsDelayType>::Option
delay_competing_low_priority_requests_delay_types[] = {
{DelayCompetingLowPriorityRequestsDelayType::kAlways, "always"},
const base::FeatureParam<DelayCompetingLowPriorityRequestsDelayType>
&kDelayCompetingLowPriorityRequests, "until",
// The priority threshold: indicates which ResourceLoadPriority should be
// considered "important", such that low priority requests are delayed behind
// in-flight "important" requests.
const base::FeatureParam<DelayCompetingLowPriorityRequestsThreshold>::Option
delay_competing_low_priority_requests_thresholds[] = {
{DelayCompetingLowPriorityRequestsThreshold::kMedium, "medium"},
{DelayCompetingLowPriorityRequestsThreshold::kHigh, "high"}};
const base::FeatureParam<DelayCompetingLowPriorityRequestsThreshold>
&kDelayCompetingLowPriorityRequests, "priority_threshold",
// The AppCache feature is a kill-switch for the entire AppCache feature,
// both backend and API. If disabled, then it will turn off the backend and
// api, regardless of the presence of valid origin trial tokens. Disabling
// AppCache will also delete any AppCache data from the profile directory.
const base::Feature kAppCache{"AppCache", base::FEATURE_ENABLED_BY_DEFAULT};
// If AppCacheRequireOriginTrial is enabled, then the AppCache backend in the
// browser will require origin trial tokens in order to load or store manifests
// and their contents.
const base::Feature kAppCacheRequireOriginTrial{
"AppCacheRequireOriginTrial", base::FEATURE_ENABLED_BY_DEFAULT};
// Enables the JPEG XL Image File Format (JXL).
const base::Feature kJXL{"JXL", base::FEATURE_DISABLED_BY_DEFAULT};
// Make all pending 'display: auto' web fonts enter the swap or failure period
// immediately before reaching the LCP time limit (~2500ms), so that web fonts
// do not become a source of bad LCP.
const base::Feature kAlignFontDisplayAutoTimeoutWithLCPGoal{
"AlignFontDisplayAutoTimeoutWithLCPGoal", base::FEATURE_ENABLED_BY_DEFAULT};
// The amount of time allowed for 'display: auto' web fonts to load without
// intervention, counted from navigation start.
const base::FeatureParam<int>
&kAlignFontDisplayAutoTimeoutWithLCPGoal, "lcp-limit-in-ms", 2000};
const base::FeatureParam<AlignFontDisplayAutoTimeoutWithLCPGoalMode>::Option
align_font_display_auto_timeout_with_lcp_goal_modes[] = {
{AlignFontDisplayAutoTimeoutWithLCPGoalMode::kToSwapPeriod, "swap"}};
const base::FeatureParam<AlignFontDisplayAutoTimeoutWithLCPGoalMode>
&kAlignFontDisplayAutoTimeoutWithLCPGoal, "intervention-mode",
// Enable throttling of fetch() requests from service workers in the
// installing state. The limit of 3 was chosen to match the limit
// in background main frames. In addition, trials showed that this
// did not cause excessive timeouts and resulted in a net improvement
// in successful install rate on some platforms.
const base::Feature kThrottleInstallingServiceWorker{
"ThrottleInstallingServiceWorker", base::FEATURE_ENABLED_BY_DEFAULT};
const base::FeatureParam<int> kInstallingServiceWorkerOutstandingThrottledLimit{
&kThrottleInstallingServiceWorker, "limit", 3};
const base::Feature kInputPredictorTypeChoice{
"InputPredictorTypeChoice", base::FEATURE_DISABLED_BY_DEFAULT};
const base::Feature kResamplingInputEvents{"ResamplingInputEvents",
const base::Feature kInputTargetClientHighPriority{
"InputTargetClientHighPriority", base::FEATURE_DISABLED_BY_DEFAULT};
const base::Feature kResamplingScrollEvents{"ResamplingScrollEvents",
// Enables the device-memory, resource-width, viewport-width and DPR client
// hints to be sent to third-party origins if the first-party has opted in to
// receiving client hints, regardless of Permissions Policy.
const base::Feature kAllowClientHintsToThirdParty {
#if defined(OS_ANDROID)
const base::Feature kFilteringScrollPrediction{
"FilteringScrollPrediction", base::FEATURE_DISABLED_BY_DEFAULT};
const base::Feature kKalmanHeuristics{"KalmanHeuristics",
const base::Feature kKalmanDirectionCutOff{"KalmanDirectionCutOff",
const base::Feature kSkipTouchEventFilter{"SkipTouchEventFilter",
const char kSkipTouchEventFilterTypeParamName[] = "type";
const char kSkipTouchEventFilterTypeParamValueDiscrete[] = "discrete";
const char kSkipTouchEventFilterTypeParamValueAll[] = "all";
const char kSkipTouchEventFilterFilteringProcessParamName[] =
const char kSkipTouchEventFilterFilteringProcessParamValueBrowser[] = "browser";
const char kSkipTouchEventFilterFilteringProcessParamValueBrowserAndRenderer[] =
// Disabling this will cause parkable strings to never be compressed.
// This is useful for headless mode + virtual time. Since virtual time advances
// quickly, strings may be parked too eagerly in that mode.
const base::Feature kCompressParkableStrings{"CompressParkableStrings",
// Whether ParkableStrings can be written out to disk.
// Depends on compression above.
const base::Feature kParkableStringsToDisk{"ParkableStringsToDisk",
bool IsParkableStringsToDiskEnabled() {
return base::FeatureList::IsEnabled(kParkableStringsToDisk) &&
// Controls whether to auto select on contextual menu click in Chrome OS.
const base::Feature kCrOSAutoSelect{"CrOSAutoSelect",
const base::Feature kCLSScrollAnchoring{"CLSScrollAnchoring",
// Reduce the amount of information in the default 'referer' header for
// cross-origin requests.
const base::Feature kReducedReferrerGranularity{
"ReducedReferrerGranularity", base::FEATURE_ENABLED_BY_DEFAULT};
// Enables the constant streaming in the ContentCapture task.
const base::Feature kContentCaptureConstantStreaming = {
"ContentCaptureConstantStreaming", base::FEATURE_ENABLED_BY_DEFAULT};
// Dispatches a fake fetch event to a service worker to check the offline
// capability of the site before promoting installation.
// See for more details.
const base::Feature kCheckOfflineCapability{"CheckOfflineCapability",
const base::FeatureParam<CheckOfflineCapabilityMode>::Option
check_offline_capability_types[] = {
{CheckOfflineCapabilityMode::kWarnOnly, "warn_only"},
{CheckOfflineCapabilityMode::kEnforce, "enforce"}};
const base::FeatureParam<CheckOfflineCapabilityMode>
kCheckOfflineCapabilityParam{&kCheckOfflineCapability, "check_mode",
// The "BackForwardCacheABExperimentControl" feature indicates the state of the
// same-site BackForwardCache experiment. This information is used when sending
// the "Sec-bfcache-experiment" HTTP Header on resource requests. The header
// value is determined by the value of the "experiment_group_for_http_header"
// feature parameter.
const base::Feature kBackForwardCacheABExperimentControl{
"BackForwardCacheABExperimentControl", base::FEATURE_DISABLED_BY_DEFAULT};
const char kBackForwardCacheABExperimentGroup[] =
// Whether we should composite a PLSA (paint layer scrollable area) even if it
// means losing lcd text.
const base::Feature kPreferCompositingToLCDText = {
"PreferCompositingToLCDText", base::FEATURE_DISABLED_BY_DEFAULT};
const base::Feature kLogUnexpectedIPCPostedToBackForwardCachedDocuments{
// Enables web apps to request isolated storage.
const base::Feature kWebAppEnableIsolatedStorage{
"WebAppEnableIsolatedStorage", base::FEATURE_DISABLED_BY_DEFAULT};
// Enables declarative link capturing in web apps.
// Explainer:
const base::Feature kWebAppEnableLinkCapturing{
"WebAppEnableLinkCapturing", base::FEATURE_DISABLED_BY_DEFAULT};
// Controls URL handling feature in web apps. Controls parsing of "url_handlers"
// field in web app manifests. See explainer for more information:
const base::Feature kWebAppEnableUrlHandlers{"WebAppEnableUrlHandlers",
// Enables Protocol handling feature in web apps. Controls parsing of
// "protocol_handlers" field in web app manifests. See explainer for more
// information:
const base::Feature kWebAppEnableProtocolHandlers{
"WebAppEnableProtocolHandlers", base::FEATURE_DISABLED_BY_DEFAULT};
// Whether web apps are able to be treated as note-taking apps. Controls parsing
// of "note_taking" dictionary field and "new_note_url" entry in web app
// manifests. Also controls whether the parsed field is used in browser. See
// incubation spec:
const base::Feature kWebAppNoteTaking{"WebAppNoteTaking",
// Makes network loading tasks unfreezable so that they can be processed while
// the page is frozen.
const base::Feature kLoadingTasksUnfreezable{"LoadingTasksUnfreezable",
// Makes freezing of frame-associated task queues happen even when KeepActive is
// true.
const base::Feature kFreezeWhileKeepActive{"FreezeWhileKeepActive",
// Kill switch for the new behavior whereby anchors with target=_blank get
// noopener behavior by default. TODO( Remove in Chrome 95.
const base::Feature kTargetBlankImpliesNoOpener{
"TargetBlankImpliesNoOpener", base::FEATURE_ENABLED_BY_DEFAULT};
// Controls how max frame rates are enforced in MediaStreamTracks.
// TODO( Remove in M91.
const base::Feature kMediaStreamTrackUseConfigMaxFrameRate{
"MediaStreamTrackUseConfigMaxFrameRate", base::FEATURE_DISABLED_BY_DEFAULT};
// When enabled, WebRTC's worker thread will run on a thread context distinct
// from the WebRTC signaling and network threads.
const base::Feature kWebRtcDistinctWorkerThread{
"WebRtcDistinctWorkerThread", base::FEATURE_DISABLED_BY_DEFAULT};
// When enabled, the SubresourceFilter receives calls from the ResourceLoader
// to perform additional checks against any aliases found from DNS CNAME records
// for the requested URL.
const base::Feature kSendCnameAliasesToSubresourceFilterFromRenderer{
// Enables the declarative Shadow DOM feature.
const base::Feature kDeclarativeShadowDOM{"DeclarativeShadowDOM",
// Kill switch for the InterestCohort API origin trial, i.e. if disabled, the
// API exposure will be disabled regardless of the OT config.
// (See
const base::Feature kInterestCohortAPIOriginTrial{
"InterestCohortAPIOriginTrial", base::FEATURE_DISABLED_BY_DEFAULT};
// Enable the availability of the "interest-cohort" permissions policy.
const base::Feature kInterestCohortFeaturePolicy{
"InterestCohortFeaturePolicy", base::FEATURE_DISABLED_BY_DEFAULT};
// Changes the default background color of the Text Fragment from
// bright yellow rgb(255, 255, 0) to light purple rgb(233, 210, 253)
const base::Feature kTextFragmentColorChange{"TextFragmentColorChange",
const base::Feature kDisableDocumentDomainByDefault{
"DisableDocumentDomainByDefault", base::FEATURE_DISABLED_BY_DEFAULT};
// Scopes the memory cache to a fetcher i.e. document/frame. Any resource cached
// in the blink cache will only be reused if the most recent fetcher that
// fetched it was the same as the current document.
const base::Feature kScopeMemoryCachePerContext{
"ScopeMemoryCachePerContext", base::FEATURE_DISABLED_BY_DEFAULT};
// Allow image context menu selections to penetrate through transparent
// elements.
const base::Feature kEnablePenetratingImageSelection{
"EnablePenetratingImageSelection", base::FEATURE_DISABLED_BY_DEFAULT};
// When enabled, permits shared/root element transitions. See
const base::Feature kDocumentTransition{"DocumentTransition",
// Used to configure a per-origin allowlist of performance.mark events that are
// permitted to be included in slow reports traces. See
const base::Feature kBackgroundTracingPerformanceMark{
"BackgroundTracingPerformanceMark", base::FEATURE_DISABLED_BY_DEFAULT};
const base::FeatureParam<std::string>
&kBackgroundTracingPerformanceMark, "allow_list", ""};
const base::Feature kCLSM90Improvements{"CLSM90Improvements",
// New compositing algorithm. See renderer/core/paint/
const base::Feature kCompositeAfterPaint{"CompositeAfterPaint",
// Controls whether the Sanitizer API is available.
const base::Feature kSanitizerAPI{"SanitizerAPI",
// Kill switch for the blocking of the navigation of top from a cross origin
// iframe to a different protocol. TODO( Remove in
// M92.
const base::Feature kBlockCrossOriginTopNavigationToDiffentScheme{
// Enables a Web API for websites to access admin-provided configuration.
const base::Feature kManagedConfiguration{"ManagedConfiguration",
// Causes all cross-origin iframes, both same-process and out-of-process, to
// have their rendering throttled on display:none or zero-area.
const base::Feature kThrottleDisplayNoneAndVisibilityHiddenCrossOriginIframes{
// Kill switch for the Fledge Interest Group API, i.e. if disabled, the
// API exposure will be disabled regardless of the OT config.
// (See
// Enables FLEDGE implementation. See
const base::Feature kFledgeInterestGroups{"FledgeInterestGroups",
// Enable the availability of the Fledge interest group API as part of the
// origin trial.
const base::Feature kFledgeInterestGroupAPI{"FledgeInterestGroupAPI",
// Enable the ability to minimize processing in the WebRTC APM when all audio
// tracks are disabled. If disabled, the APM in WebRTC will ignore attempts to
// set it in a low-processing mode when all audio tracks are disabled.
const base::Feature kMinimizeAudioProcessingForUnusedOutput{
// When <dialog>s are closed, this focuses the "previously focused" element
// which had focus when the <dialog> was first opened.
// TODO( Remove DialogFocusNewSpecBehavior after
// the feature is in stable with no issues.
const base::Feature kDialogFocusNewSpecBehavior{
"DialogFocusNewSpecBehavior", base::FEATURE_ENABLED_BY_DEFAULT};
// Makes autofill look across shadow boundaries when collecting form controls to
// fill.
const base::Feature kAutofillShadowDOM{"AutofillShadowDOM",
} // namespace features
} // namespace blink