chrome: Cleanup class/struct forward declarations

chrome/browser/extensions/sync_bundle.h

 // Copyright 2013 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_EXTENSIONS_SYNC_BUNDLE_H_
 #define CHROME_BROWSER_EXTENSIONS_SYNC_BUNDLE_H_
 
 #include <memory>
 #include <set>
 #include <string>
 
 #include "base/macros.h"
 #include "components/sync/model/sync_change.h"
 #include "components/sync/model/sync_change_processor.h"
 #include "components/sync/model/sync_data.h"
 
-class ExtensionSyncService;
-
 namespace extensions {
 
 class ExtensionSyncData;
 
 class SyncBundle {
  public:
   SyncBundle();
   ~SyncBundle();
 
   void StartSyncing(
@@ skipping 60 matching lines @@
   // server until we've installed the extension locally, to prevent the sync
   // state from flipping back and forth until all clients are up to date.
   std::map<std::string, ExtensionSyncData> pending_sync_data_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncBundle);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_SYNC_BUNDLE_H_