content: Cleanup class/struct forward declarations

content/public/browser/background_sync_controller.h

 // Copyright 2015 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 CONTENT_PUBLIC_BROWSER_BACKGROUND_SYNC_CONTROLLER_H_
 #define CONTENT_PUBLIC_BROWSER_BACKGROUND_SYNC_CONTROLLER_H_
 
 #include <stdint.h>
 
 #include "content/common/content_export.h"
 #include "url/gurl.h"
 
 namespace content {
 
-class BackgroundSyncManager;
-
 struct BackgroundSyncParameters;
 
 // An interface that the Background Sync API uses to access services from the
 // embedder. Must only be used on the UI thread.
 class CONTENT_EXPORT BackgroundSyncController {
  public:
   virtual ~BackgroundSyncController() {}
 
   // This function allows the controller to alter the parameters used by
   // background sync. Note that disable can be overridden from false to true
@@ skipping 13 matching lines @@
   //
   // * Other Platforms: (UNIMPLEMENTED) Keeps the browser alive via
   // BackgroundModeManager until called with |enabled| = false. |min_ms| is
   // ignored.
   virtual void RunInBackground(bool enabled, int64_t min_ms) {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_BACKGROUND_SYNC_CONTROLLER_H_