[iOS] Add a flag for new sign-out feature.

Bug: 1005509
Change-Id: I7eab2ad6ad082daadff0ab38aafe9ea57d655ccb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2007450
Commit-Queue: Nohemi Fernandez <fernandex@chromium.org>
Reviewed-by: Stepan Khapugin <stkhapugin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732881}

ios/chrome/browser/flags/about_flags.mm

@@ -601,6 +601,9 @@ const flags_ui::FeatureEntry kFeatureEntries[] = {
     {"contained-browser-bvc", flag_descriptions::kContainedBVCName,
      flag_descriptions::kContainedBVCDescription, flags_ui::kOsIos,
      FEATURE_VALUE_TYPE(kContainedBVC)},
+    {"clear-synced-data", flag_descriptions::kClearSyncedDataName,
+     flag_descriptions::kClearSyncedDataDescription, flags_ui::kOsIos,
+     FEATURE_VALUE_TYPE(kClearSyncedData)},
 };
 
 // Add all switches from experimental flags to |command_line|.

ios/chrome/browser/flags/ios_chrome_flag_descriptions.cc

@@ -120,6 +120,12 @@ const char kBrowserContainerKeepsContentViewDescription[] =
     "When enable, the browser container keeps the content view in the view "
     "hierarchy, to avoid WKWebView from being unloaded from the process.";
 
+const char kClearSyncedDataName[] = "Clear Synced Data on Sign Out";
+const char kClearSyncedDataDescription[] =
+    "When enabled users signed in with a non-managed account will be "
+    "presented with the option to clear synced data from the local "
+    "device when signing out.";
+
 const char kCollectionsCardPresentationStyleName[] =
     "Card style presentation for Collections.";
 const char kCollectionsCardPresentationStyleDescription[] =

ios/chrome/browser/flags/ios_chrome_flag_descriptions.h

@@ -93,6 +93,11 @@ extern const char kBreakpadNoDelayInitialUploadDescription[];
 extern const char kBrowserContainerKeepsContentViewName[];
 extern const char kBrowserContainerKeepsContentViewDescription[];
 
+// Title and description for the flag to control if Chrome should wipe synced
+// data from a local device on sign-out from a non-managed account.
+extern const char kClearSyncedDataName[];
+extern const char kClearSyncedDataDescription[];
+
 // Title and description for the flag that controls whether Collections are
 // presented using the new iOS13 Card style or the custom legacy one.
 extern const char kCollectionsCardPresentationStyleName[];

ios/chrome/browser/ui/ui_feature_flags.cc

@@ -36,3 +36,6 @@ const base::Feature kForceUnstackedTabstrip{"ForceUnstackedTabstrip",
 
 const base::Feature kContainedBVC{"ContainedBVC",
                                   base::FEATURE_DISABLED_BY_DEFAULT};
+
+const base::Feature kClearSyncedData{"ClearSyncedData",
+                                     base::FEATURE_DISABLED_BY_DEFAULT};

ios/chrome/browser/ui/ui_feature_flags.h

@@ -40,4 +40,8 @@ extern const base::Feature kForceUnstackedTabstrip;
 // presented.
 extern const base::Feature kContainedBVC;
 
+// Feature flag to display a new option that wipes synced data on a local
+// device when signing out from a non-managed account.
+extern const base::Feature kClearSyncedData;
+
 #endif  // IOS_CHROME_BROWSER_UI_UI_FEATURE_FLAGS_H_