Add a chrome://flags entry for AlignFontDisplayAutoTimeoutsWithLCP

Bug: 1065508
Change-Id: Ieb3d033e514a3815743129ce881dfd5c3c08a121
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2149907Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#760278}

chrome/browser/about_flags.cc

@@ -5264,6 +5264,13 @@ const FeatureEntry kFeatureEntries[] = {
      FEATURE_VALUE_TYPE(
          autofill::features::kAutofillEnableStickyPaymentsBubble)},
 
+    {"align-font-display-auto-lcp",
+     flag_descriptions::kAlignFontDisplayAutoTimeoutWithLCPGoalName,
+     flag_descriptions::kAlignFontDisplayAutoTimeoutWithLCPGoalDescription,
+     kOsAll,
+     FEATURE_VALUE_TYPE(
+         blink::features::kAlignFontDisplayAutoTimeoutWithLCPGoal)},
+
     // NOTE: Adding a new flag requires adding a corresponding entry to enum
     // "LoginCustomFlags" in tools/metrics/histograms/enums.xml. See "Flag
     // Histograms" in tools/metrics/histograms/README.md (run the

chrome/browser/flag-metadata.json

@@ -48,6 +48,11 @@
     "owners": [ "thanhdng", "jiameng" ],
     "expiry_milestone": 82
   },
+  {
+    "name": "align-font-display-auto-lcp",
+    "owners": [ "xiaochengh" ],
+    "expiry_milestone": 85
+  },
   {
     "name": "allow-disable-mouse-acceleration",
     "owners": [ "zentaro" ],

chrome/browser/flag_descriptions.cc

@@ -39,6 +39,13 @@ const char kAccountIdMigrationDescription[] =
     "Migrate to use Gaia ID instead of the email as the account identifer for "
     "the Identity Manager.";
 
+const char kAlignFontDisplayAutoTimeoutWithLCPGoalName[] =
+    "Align 'font-display: auto' timeout with LCP goal";
+const char kAlignFontDisplayAutoTimeoutWithLCPGoalDescription[] =
+    "Make all pending 'display: auto' web fonts enter the failure period "
+    "immediately before reaching the LCP time limit (~2500ms), so that web "
+    "fonts do not become a source of bad LCP (Largest Contentful Paint).";
+
 const char kAllowInsecureLocalhostName[] =
     "Allow invalid certificates for resources loaded from localhost.";
 const char kAllowInsecureLocalhostDescription[] =

chrome/browser/flag_descriptions.h

@@ -60,6 +60,9 @@ extern const char kAccessibilityExposeDisplayNoneDescription[];
 extern const char kAccountIdMigrationName[];
 extern const char kAccountIdMigrationDescription[];
 
+extern const char kAlignFontDisplayAutoTimeoutWithLCPGoalName[];
+extern const char kAlignFontDisplayAutoTimeoutWithLCPGoalDescription[];
+
 extern const char kAllowInsecureLocalhostName[];
 extern const char kAllowInsecureLocalhostDescription[];
 

tools/metrics/histograms/enums.xml

@@ -38202,6 +38202,8 @@ from previous Chrome versions.
   <int value="-1605567628" label="disable-overlay-scrollbar"/>
   <int value="-1604051051" label="SpecialLocale:disabled"/>
   <int value="-1603404046" label="V8VmFuture:disabled"/>
+  <int value="-1603026968"
+      label="AlignFontDisplayAutoTimeoutWithLCPGoal:disabled"/>
   <int value="-1601374850" label="DialMediaRouteProvider:disabled"/>
   <int value="-1599538279" label="enable-md-policy-page"/>
   <int value="-1596859081" label="WebAuthenticationPINSupport:enabled"/>
@@ -38629,6 +38631,8 @@ from previous Chrome versions.
   <int value="-1154394293"
       label="UpdateNotificationScheduleServiceImmediateShowOption:enabled"/>
   <int value="-1154343236" label="VrBrowsingTabsView:disabled"/>
+  <int value="-1153892430"
+      label="AlignFontDisplayAutoTimeoutWithLCPGoal:enabled"/>
   <int value="-1151766565" label="enable-fullscreen-tab-detaching"/>
   <int value="-1145905507" label="SendTabToSelfWhenSignedIn:disabled"/>
   <int value="-1145702446" label="ChromeHomeInactivitySheetExpansion:enabled"/>