Add chrome://flags entry for account-scoped preferences

This CL adds a chrome://flags entry for
syncer::kEnablePreferencesAccountStorage (for both iOS and other
platforms).

Bug: 1416480
Change-Id: I7b931ff56f300fef83ff3ffd0d2ba6b4b73885ef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4334360
Reviewed-by: Maksim Moskvitin <[email protected]>
Commit-Queue: Marc Treib <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1116868}
diff --git a/ios/chrome/browser/flags/about_flags.mm b/ios/chrome/browser/flags/about_flags.mm
index 193d647..af61c18 100644
--- a/ios/chrome/browser/flags/about_flags.mm
+++ b/ios/chrome/browser/flags/about_flags.mm
@@ -1442,6 +1442,11 @@
      flags_ui::kOsIos,
      FEATURE_VALUE_TYPE(
          autofill::features::kAutofillUpstreamAuthenticatePreflightCall)},
+    {"enable-preferences-account-storage",
+     flag_descriptions::kEnablePreferencesAccountStorageName,
+     flag_descriptions::kEnablePreferencesAccountStorageDescription,
+     flags_ui::kOsIos,
+     FEATURE_VALUE_TYPE(syncer::kEnablePreferencesAccountStorage)},
 };
 
 bool SkipConditionalFeatureEntry(const flags_ui::FeatureEntry& entry) {
diff --git a/ios/chrome/browser/flags/ios_chrome_flag_descriptions.cc b/ios/chrome/browser/flags/ios_chrome_flag_descriptions.cc
index 9d04d537..e4bb1ce 100644
--- a/ios/chrome/browser/flags/ios_chrome_flag_descriptions.cc
+++ b/ios/chrome/browser/flags/ios_chrome_flag_descriptions.cc
@@ -370,6 +370,12 @@
     "Enables storing passwords in a second, Gaia-account-scoped storage for "
     "signed-in but not syncing users";
 
+const char kEnablePreferencesAccountStorageName[] =
+    "Enable the account data storage for preferences for syncing users";
+const char kEnablePreferencesAccountStorageDescription[] =
+    "Enables storing preferences in a second, Gaia-account-scoped storage for "
+    "syncing users";
+
 const char kEnablePinnedTabsName[] = "Enable Pinned Tabs";
 const char kEnablePinnedTabsDescription[] = "Allows users to pin tabs.";
 
diff --git a/ios/chrome/browser/flags/ios_chrome_flag_descriptions.h b/ios/chrome/browser/flags/ios_chrome_flag_descriptions.h
index f0061ac..2163fce 100644
--- a/ios/chrome/browser/flags/ios_chrome_flag_descriptions.h
+++ b/ios/chrome/browser/flags/ios_chrome_flag_descriptions.h
@@ -327,6 +327,10 @@
 extern const char kEnablePasswordsAccountStorageName[];
 extern const char kEnablePasswordsAccountStorageDescription[];
 
+// Title and description for the flag to enable the preferences account storage.
+extern const char kEnablePreferencesAccountStorageName[];
+extern const char kEnablePreferencesAccountStorageDescription[];
+
 // Title and description for the flag to enable pinned tabs.
 extern const char kEnablePinnedTabsName[];
 extern const char kEnablePinnedTabsDescription[];