[sync] Prevent flash of error icon while loading syncSetup page

chrome/browser/ui/webui/settings/people_handler.h

Index: chrome/browser/ui/webui/settings/people_handler.h
diff --git a/chrome/browser/ui/webui/settings/people_handler.h b/chrome/browser/ui/webui/settings/people_handler.h
index 7b587f71633eb0597223b66936e8f18f8f80e7ed..2f73c1b4901663eac98a2992f597c4d2a3f1404a 100644
--- a/chrome/browser/ui/webui/settings/people_handler.h
+++ b/chrome/browser/ui/webui/settings/people_handler.h
@@ -98,6 +98,8 @@ class PeopleHandler : public SettingsPageUIHandler,
   FRIEND_TEST_ALL_PREFIXES(PeopleHandlerNonCrosTest,
                            SubmitAuthWithInvalidUsername);
   FRIEND_TEST_ALL_PREFIXES(PeopleHandlerFirstSigninTest, DisplayBasicLogin);
+  FRIEND_TEST_ALL_PREFIXES(PeopleHandlerTest,
+                           AcquireSyncBlockerWhenLoadingSyncSettingsSubpage);
 
   // SettingsPageUIHandler implementation.
   void RegisterMessages() override;
@@ -174,6 +176,9 @@ class PeopleHandler : public SettingsPageUIHandler,
   // Suppresses any further signin promos, since the user has signed in once.
   void MarkFirstSetupComplete();
 
+  // Maybe acquire a SyncSetupInProgressHandle and store it in sync_blocker_.
+  void MaybeAcquireSyncBlocker();
+
   // Weak pointer.
   Profile* profile_;