Cleanup: Remove unneeded forward declarations from chrome/browser/extensions.

chrome/browser/extensions/extension_sync_data.h

 // Copyright (c) 2011 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_EXTENSION_SYNC_DATA_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_SYNC_DATA_H_
 #pragma once
 
 #include <string>
 
 #include "base/version.h"
 #include "chrome/browser/sync/api/sync_change.h"
 #include "chrome/browser/sync/api/sync_data.h"
 #include "chrome/common/extensions/extension.h"
 #include "googleurl/src/gurl.h"
 
-class ExtensionService;
 class SyncData;
 namespace sync_pb {
 class AppSpecifics;
 class ExtensionSpecifics;
 }
 
 // A class that encapsulates the synced properties of an Extension.
 class ExtensionSyncData {
  public:
   ExtensionSyncData();
@@ skipping 48 matching lines @@
   bool incognito_enabled_;
   Extension::SyncType type_;
   Version version_;
   GURL update_url_;
   std::string name_;
   bool notifications_initial_setup_done_;
   bool notifications_disabled_;
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_SYNC_DATA_H_