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

content/browser/renderer_host/media/video_capture_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.
 //
 // VideoCaptureHost serves video capture related messages from
 // VideCaptureMessageFilter which lives inside the render process.
 //
 // This class is owned by BrowserRenderProcessHost, and instantiated on UI
 // thread, but all other operations and method calls happen on IO thread.
 //
@@ skipping 27 matching lines @@
 
 #include <map>
 
 #include "base/memory/ref_counted.h"
 #include "base/sequenced_task_runner_helpers.h"
 #include "content/browser/renderer_host/media/video_capture_controller.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/browser_message_filter.h"
 #include "ipc/ipc_message.h"
 
-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);
+  VideoCaptureHost();
 
   // content::BrowserMessageFilter implementation.
   virtual void OnChannelClosing() OVERRIDE;
   virtual void OnDestruct() const OVERRIDE;
   virtual bool OnMessageReceived(const IPC::Message& message,
                                  bool* message_was_ok) OVERRIDE;
 
   // VideoCaptureControllerEventHandler implementation.
   virtual void OnError(const VideoCaptureControllerID& id) OVERRIDE;
   virtual void OnBufferCreated(const VideoCaptureControllerID& id,
@@ skipping 61 matching lines @@
       int frame_per_second);
 
   // Handle error coming from VideoCaptureDevice.
   void DoHandleErrorOnIOThread(const VideoCaptureControllerID& controller_id);
 
   void DoPausedOnIOThread(const VideoCaptureControllerID& controller_id);
 
   void DeleteVideoCaptureControllerOnIOThread(
       const VideoCaptureControllerID& controller_id);
 
-  // Helpers.
-  media_stream::VideoCaptureManager* GetVideoCaptureManager();
+  // Returns the video capture manager. This is a virtual function so that
+  // the unit tests can inject their own MediaStreamManager.
+  virtual media_stream::VideoCaptureManager* GetVideoCaptureManager();
 
   struct Entry;
   typedef std::map<VideoCaptureControllerID, Entry*> EntryMap;
   // A map of VideoCaptureControllerID to its state and VideoCaptureController.
   EntryMap entries_;
 
-  // 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);
 };
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_HOST_H_