[Sync] Don't display passphrase notification if user dismissed previous one

chrome/browser/sync/sync_error_notifier_ash.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_SYNC_SYNC_ERROR_NOTIFIER_ASH_H_
 #define CHROME_BROWSER_SYNC_SYNC_ERROR_NOTIFIER_ASH_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
@@ skipping 17 matching lines @@
   // syncer::SyncErrorController::Observer:
   void OnErrorChanged() override;
 
  private:
   // The error controller to query for error details.
   syncer::SyncErrorController* error_controller_;
 
   // The Profile this service belongs to.
   Profile* profile_;
 
+  // Notification was added to NotificationUIManager. This flag is used to
+  // prevent displaying passphrase notification to user if they already saw (and
+  // potentially dismissed) previous one.
+  bool notification_displayed_;
+
   // Used to keep track of the message center notification.
   std::string notification_id_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncErrorNotifier);
 };
 
 #endif  // CHROME_BROWSER_SYNC_SYNC_ERROR_NOTIFIER_ASH_H_