content: Cleanup class/struct forward declarations

content/public/browser/background_tracing_manager.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_TRACING_MANAGER_H_
 #define CONTENT_PUBLIC_BROWSER_BACKGROUND_TRACING_MANAGER_H_
 
 #include <memory>
 
 #include "base/trace_event/trace_event_impl.h"
 #include "base/values.h"
 #include "content/common/content_export.h"
 
 namespace content {
 class BackgroundTracingConfig;
-struct BackgroundTracingUploadConfig;
 
 // BackgroundTracingManager is used on the browser process to trigger the
 // collection of trace data and upload the results. Only the browser UI thread
 // is allowed to interact with the BackgroundTracingManager. All callbacks are
 // called on the UI thread.
 class BackgroundTracingManager {
  public:
   CONTENT_EXPORT static BackgroundTracingManager* GetInstance();
 
   // ReceiveCallback will will be called on the UI thread every time the
@@ skipping 71 matching lines @@
       const base::Closure& callback) = 0;
   virtual void FireTimerForTesting() = 0;
 
  protected:
   virtual ~BackgroundTracingManager() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_BACKGROUND_TRACING_MANAGER_H_