Added feature flag for percent-based scrolling.

Bug: 1007464
Change-Id: Ia3daa354ae93f2d2fb99f0b289df1e0a8e4190f8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1819777
Commit-Queue: Matt Amert <Matthew.Amert@microsoft.com>
Reviewed-by: Daniel Libby <dlibby@microsoft.com>
Reviewed-by: David Bokan <bokan@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#699927}

chrome/browser/about_flags.cc

@@ -4614,6 +4614,10 @@ const FeatureEntry kFeatureEntries[] = {
      FEATURE_VALUE_TYPE(omnibox::kOmniboxRemoveSuggestionsFromClipboard)},
 #endif  // defined(OS_ANDROID)
 
+    {"percent-based-scrolling", flag_descriptions::kPercentBasedScrollingName,
+     flag_descriptions::kPercentBasedScrollingDescription, kOsAll,
+     FEATURE_VALUE_TYPE(features::kPercentBasedScrolling)},
+
     // 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

@@ -2857,6 +2857,11 @@
     "owners": [ "rouslan" ],
     "expiry_milestone": 78
   },
+  {
+    "name": "percent-based-scrolling",
+    "owners": [ "maamert@microsoft.com" ],
+    "expiry_milestone": 82
+  },
   {
     "name": "periodic-background-sync",
     "owners": [ "nator" ],

chrome/browser/flag_descriptions.cc

@@ -1600,6 +1600,11 @@ const char kForceWebContentsDarkModeName[] = "Force Dark Mode for Web Contents";
 const char kForceWebContentsDarkModeDescription[] =
     "Automatically render all web contents using a dark theme.";
 
+const char kPercentBasedScrollingName[] = "Percent-based Scrolling";
+const char kPercentBasedScrollingDescription[] =
+    "If enabled, mousewheel and keyboard scrolls will scroll by a percentage "
+    "of the scroller size.";
+
 const char kPeriodicBackgroundSyncName[] = "Periodic Background Sync";
 const char kPeriodicBackgroundSyncDescription[] =
     "If enabled, web apps can periodically sync content in the background.";

chrome/browser/flag_descriptions.h

@@ -961,6 +961,9 @@ extern const char kPasswordLeakDetectionDescription[];
 extern const char kForceWebContentsDarkModeName[];
 extern const char kForceWebContentsDarkModeDescription[];
 
+extern const char kPercentBasedScrollingName[];
+extern const char kPercentBasedScrollingDescription[];
+
 extern const char kPeriodicBackgroundSyncName[];
 extern const char kPeriodicBackgroundSyncDescription[];
 

tools/metrics/histograms/enums.xml

@@ -36629,6 +36629,7 @@ from previous Chrome versions.
   <int value="288012253" label="CrostiniFiles:enabled"/>
   <int value="288755982"
       label="AutofillEnableLocalCardMigrationForNonSyncUser:enabled"/>
+  <int value="291389947" label="PercentBasedScrolling:disabled"/>
   <int value="291482671" label="ExperimentalFlingAnimation:disabled"/>
   <int value="292560715" label="ViewsCastDialog:disabled"/>
   <int value="293134455" label="AutofillSendBillingCustomerNumber:disabled"/>
@@ -36777,6 +36778,7 @@ from previous Chrome versions.
   <int value="479906041" label="RunAllFlashInAllowMode:disabled"/>
   <int value="480544447" label="NonValidatingReloadOnRefreshContentV2:enabled"/>
   <int value="481506759" label="ServiceWorkerScriptStreaming:enabled"/>
+  <int value="482232604" label="PercentBasedScrolling:enabled"/>
   <int value="492113129" label="ExperimentalAppBanners:enabled"/>
   <int value="492985975" label="use-monitor-color-space"/>
   <int value="493903641" label="disable-appcontainer"/>

ui/base/ui_base_features.cc

@@ -28,6 +28,11 @@ const base::Feature kSettingsShowsPerKeyboardSettings = {
 const base::Feature kInputMethodSettingsUiUpdate = {
     "InputMethodSettingsUiUpdate", base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Enables percent-based scrolling for mousewheel and keyboard initiated
+// scrolls.
+const base::Feature kPercentBasedScrolling = {
+    "PercentBasedScrolling", base::FEATURE_DISABLED_BY_DEFAULT};
+
 // Allows requesting unadjusted movement when entering pointerlock.
 const base::Feature kPointerLockOptions = {"PointerLockOptions",
                                            base::FEATURE_DISABLED_BY_DEFAULT};

ui/base/ui_base_features.h

@@ -23,6 +23,8 @@ extern const base::Feature kSettingsShowsPerKeyboardSettings;
 COMPONENT_EXPORT(UI_BASE_FEATURES)
 extern const base::Feature kInputMethodSettingsUiUpdate;
 COMPONENT_EXPORT(UI_BASE_FEATURES)
+extern const base::Feature kPercentBasedScrolling;
+COMPONENT_EXPORT(UI_BASE_FEATURES)
 extern const base::Feature kPointerLockOptions;
 COMPONENT_EXPORT(UI_BASE_FEATURES)
 extern const base::Feature kSystemCaptionStyle;