Reduce frequency of requesting bookmark clusters.

chrome/browser/enhanced_bookmarks/chrome_bookmark_server_cluster_service.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_ENHANCED_BOOKMARKS_CHROME_BOOKMARK_SERVER_CLUSTER_SERVICE_H_
 #define CHROME_BROWSER_ENHANCED_BOOKMARKS_CHROME_BOOKMARK_SERVER_CLUSTER_SERVICE_H_
 
 #include "chrome/browser/sync/profile_sync_service_observer.h"
 #include "components/enhanced_bookmarks/bookmark_server_cluster_service.h"
 
@@ skipping 15 matching lines @@
       ProfileSyncService* sync_service);
   ~ChromeBookmarkServerClusterService() override;
 
   // BookmarkServerClusterService
   void AddObserver(BookmarkServerServiceObserver* observer) override;
 
   // ProfileSyncServiceObserver implementation.
   void OnStateChanged() override;
   void OnSyncCycleCompleted() override;
 
+  // EnhancedBookmarkModelObserver implementation.
+  void EnhancedBookmarkAdded(const BookmarkNode* node) override;
+  void EnhancedBookmarkRemoved(const BookmarkNode* node) override;
  private:
+  // This sets an internal flag to fetch new clusters.
+  void InvalidateCache();
+
   // This class observes the sync service for changes.
   ProfileSyncService* sync_service_;
   bool sync_refresh_skipped_ = false;
+  // This holds the number of cluster refreshes needed.
+  int refreshes_needed_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeBookmarkServerClusterService);
 };
 
 }  // namespace enhanced_bookmarks
 
 #endif  // CHROME_BROWSER_ENHANCED_BOOKMARKS_CHROME_BOOKMARK_SERVER_CLUSTER_SERVICE_H_