content: Cleanup class/struct forward declarations

content/browser/renderer_host/media/audio_renderer_host.h

 // Copyright (c) 2012 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.
 //
 // AudioRendererHost serves audio related requests from AudioRenderer which
 // lives inside the render process and provide access to audio hardware.
 //
 // This class is owned by RenderProcessHostImpl, and instantiated on UI
 // thread, but all other operations and method calls happen on IO thread, so we
 // need to be extra careful about the lifetime of this object. AudioManager is a
@@ skipping 58 matching lines @@
 namespace media {
 class AudioManager;
 class AudioParameters;
 }
 
 namespace content {
 
 class AudioMirroringManager;
 class MediaInternals;
 class MediaStreamManager;
-class ResourceContext;
 
 class CONTENT_EXPORT AudioRendererHost : public BrowserMessageFilter {
  public:
   // Called from UI thread from the owner of this object.
   AudioRendererHost(int render_process_id,
                     media::AudioManager* audio_manager,
                     AudioMirroringManager* mirroring_manager,
                     MediaInternals* media_internals,
                     MediaStreamManager* media_stream_manager,
                     const std::string& salt);
@@ skipping 188 matching lines @@
   // The maximum number of simultaneous streams during the lifetime of this
   // host. Reported as UMA stat at shutdown.
   size_t max_simultaneous_streams_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioRendererHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_RENDERER_HOST_H_