Move the device enumerate/open/close work to device thread from IO thread

content/browser/renderer_host/media/video_capture_host.h

Index: content/browser/renderer_host/media/video_capture_host.h
diff --git a/content/browser/renderer_host/media/video_capture_host.h b/content/browser/renderer_host/media/video_capture_host.h
index a66f475b6b72db061aac4f8e99f9742eded5330b..4af3b26fc07cb60f1fefb764779411116adbb5f8 100644
--- a/content/browser/renderer_host/media/video_capture_host.h
+++ b/content/browser/renderer_host/media/video_capture_host.h
@@ -49,16 +49,11 @@ namespace content {
 class ResourceContext;
 }  // namespace content
 
-namespace media {
-class AudioManager;
-}
-
 class CONTENT_EXPORT VideoCaptureHost
     : public content::BrowserMessageFilter,
       public VideoCaptureControllerEventHandler {
  public:
-  explicit VideoCaptureHost(content::ResourceContext* resource_context,
-                            media::AudioManager* audio_manager);
+  explicit VideoCaptureHost(content::ResourceContext* resource_context);
 
   // content::BrowserMessageFilter implementation.
   virtual void OnChannelClosing() OVERRIDE;
@@ -150,7 +145,6 @@ class CONTENT_EXPORT VideoCaptureHost
 
   // Used to get a pointer to VideoCaptureManager to start/stop capture devices.
   content::ResourceContext* resource_context_;
-  media::AudioManager* audio_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoCaptureHost);
 };