handle the case when device is closed before media pipeline is fully initialized.

content/browser/renderer_host/media/video_capture_manager.h

Index: content/browser/renderer_host/media/video_capture_manager.h
===================================================================
--- content/browser/renderer_host/media/video_capture_manager.h	(revision 138673)
+++ content/browser/renderer_host/media/video_capture_manager.h	(working copy)
@@ -22,6 +22,7 @@
 #include "media/video/capture/video_capture_device.h"
 #include "media/video/capture/video_capture_types.h"
 
+class MockVideoCaptureManager;
 class VideoCaptureController;
 class VideoCaptureControllerEventHandler;
 
@@ -54,18 +55,18 @@
   // Start allocates the device and no other application can use the device
   // before Stop is called. Captured video frames will be delivered to
   // video_capture_receiver.
-  void Start(const media::VideoCaptureParams& capture_params,
+  virtual void Start(const media::VideoCaptureParams& capture_params,
              media::VideoCaptureDevice::EventHandler* video_capture_receiver);
 
   // Stops capture device referenced by |capture_session_id|. No more frames
   // will be delivered to the frame receiver, and |stopped_cb| will be called.
   // |stopped_cb| can be NULL.
-  void Stop(const media::VideoCaptureSessionId& capture_session_id,
+  virtual void Stop(const media::VideoCaptureSessionId& capture_session_id,
             base::Closure stopped_cb);
 
   // A capture device error has occurred for |capture_session_id|. The device
   // won't stream any more captured frames.
-  void Error(const media::VideoCaptureSessionId& capture_session_id);
+  virtual void Error(const media::VideoCaptureSessionId& capture_session_id);
 
   // Used by unit test to make sure a fake device is used instead of a real
   // video capture device. Due to timing requirements, the function must be
@@ -85,6 +86,7 @@
       VideoCaptureControllerEventHandler* handler);
 
  private:
+  friend class ::MockVideoCaptureManager;
   friend class base::RefCountedThreadSafe<VideoCaptureManager>;
   virtual ~VideoCaptureManager();