[Magnifier] Gate focus following toggle behind feature flag

Gate "Zoomed in screen follows keyboard focus" toggle in Chrome OS Accessibility settings behind feature flag MagnifierPanningImprovements. (following crbug.com/1144947, hide toggle in M89)

Feature off: https://screenshot.googleplex.com/8wTtrRRQCC4XNx5
Feature on: https://screenshot.googleplex.com/7RaUNBhcpQsgBeC

AX-Relnotes: N/A.
Fixed: 1165650
Change-Id: I8286f977a6099cdc31e82b536d09e5c291aac637
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2622716
Auto-Submit: Josiah Krutz <josiahk@google.com>
Commit-Queue: Jimmy Gong <jimmyxgong@chromium.org>
Reviewed-by: David Tseng <dtseng@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Reviewed-by: Jimmy Gong <jimmyxgong@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842681}

chrome/browser/resources/settings/chromeos/os_a11y_page/manage_a11y_page.html

@@ -96,15 +96,17 @@
         deep-link-focus-id$="[[Setting.kFullscreenMagnifier]]">
     </settings-toggle-button>
     <template is="dom-if" if="[[prefs.settings.a11y.screen_magnifier.value]]">
-      <div class="sub-item">
-        <settings-toggle-button
-            class="sub-item"
-            pref="{{prefs.settings.a11y.screen_magnifier_focus_following}}"
-            label="$i18n{screenMagnifierFocusFollowingLabel}"
-            deep-link-focus-id$=
-                "[[Setting.kFullscreenMagnifierFocusFollowing]]">
-        </settings-toggle-button>
-      </div>
+      <template is="dom-if" if="[[isMagnifierPanningImprovementsEnabled_]]">
+        <div class="sub-item">
+          <settings-toggle-button
+              class="sub-item"
+              pref="{{prefs.settings.a11y.screen_magnifier_focus_following}}"
+              label="$i18n{screenMagnifierFocusFollowingLabel}"
+              deep-link-focus-id$=
+                  "[[Setting.kFullscreenMagnifierFocusFollowing]]">
+          </settings-toggle-button>
+        </div>
+      </template>
       <div class="settings-box continuation">
         <div class="start sub-item settings-box-text" aria-hidden="true">
           $i18n{screenMagnifierZoomLabel}

chrome/browser/resources/settings/chromeos/os_a11y_page/manage_a11y_page.js

@@ -158,6 +158,14 @@ Polymer({
       },
     },
 
+    /** @private */
+    isMagnifierPanningImprovementsEnabled_: {
+      type: Boolean,
+      value() {
+        return loadTimeData.getBoolean('isMagnifierPanningImprovementsEnabled');
+      },
+    },
+
     /**
      * Whether the user is in kiosk mode.
      * @private

chrome/browser/ui/webui/settings/chromeos/accessibility_section.cc

@@ -196,12 +196,6 @@ const std::vector<SearchConcept>& GetA11ySearchConcepts() {
        mojom::SearchResultDefaultRank::kMedium,
        mojom::SearchResultType::kSetting,
        {.setting = mojom::Setting::kFullscreenMagnifier}},
-      {IDS_OS_SETTINGS_TAG_A11Y_FULLSCREEN_MAGNIFIER_FOCUS_FOLLOWING,
-       mojom::kManageAccessibilitySubpagePath,
-       mojom::SearchResultIcon::kA11y,
-       mojom::SearchResultDefaultRank::kMedium,
-       mojom::SearchResultType::kSetting,
-       {.setting = mojom::Setting::kFullscreenMagnifierFocusFollowing}},
       {IDS_OS_SETTINGS_TAG_A11Y_ENABLE_SWITCH_ACCESS,
        mojom::kManageAccessibilitySubpagePath,
        mojom::SearchResultIcon::kA11y,
@@ -321,6 +315,19 @@ const std::vector<SearchConcept>& GetA11yCursorColorSearchConcepts() {
   return *tags;
 }
 
+const std::vector<SearchConcept>&
+GetA11yFullscreenMagnifierFocusFollowingSearchConcepts() {
+  static const base::NoDestructor<std::vector<SearchConcept>> tags({
+      {IDS_OS_SETTINGS_TAG_A11Y_FULLSCREEN_MAGNIFIER_FOCUS_FOLLOWING,
+       mojom::kManageAccessibilitySubpagePath,
+       mojom::SearchResultIcon::kA11y,
+       mojom::SearchResultDefaultRank::kMedium,
+       mojom::SearchResultType::kSetting,
+       {.setting = mojom::Setting::kFullscreenMagnifierFocusFollowing}},
+  });
+  return *tags;
+}
+
 bool AreExperimentalA11yLabelsAllowed() {
   return base::FeatureList::IsEnabled(
       ::features::kExperimentalAccessibilityLabels);
@@ -334,6 +341,10 @@ bool IsCursorColorAllowed() {
   return features::IsAccessibilityCursorColorEnabled();
 }
 
+bool IsMagnifierPanningImprovementsEnabled() {
+  return features::IsMagnifierPanningImprovementsEnabled();
+}
+
 bool IsSwitchAccessTextAllowed() {
   return base::CommandLine::ForCurrentProcess()->HasSwitch(
       ::switches::kEnableExperimentalAccessibilitySwitchAccessText);
@@ -644,6 +655,9 @@ void AccessibilitySection::AddLoadTimeData(
   html_source->AddBoolean("showExperimentalAccessibilityCursorColor",
                           IsCursorColorAllowed());
 
+  html_source->AddBoolean("isMagnifierPanningImprovementsEnabled",
+                          IsMagnifierPanningImprovementsEnabled());
+
   ::settings::AddCaptionSubpageStrings(html_source);
 }
 
@@ -831,6 +845,14 @@ void AccessibilitySection::UpdateSearchTags() {
     updater.RemoveSearchTags(GetA11yCursorColorSearchConcepts());
   }
 
+  if (IsMagnifierPanningImprovementsEnabled()) {
+    updater.AddSearchTags(
+        GetA11yFullscreenMagnifierFocusFollowingSearchConcepts());
+  } else {
+    updater.RemoveSearchTags(
+        GetA11yFullscreenMagnifierFocusFollowingSearchConcepts());
+  }
+
   if (!pref_service_->GetBoolean(
           ash::prefs::kAccessibilitySwitchAccessEnabled)) {
     return;