Make VideoCaptureController single-threaded and not ref counted.

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 d835b6cb3183c77e4ab67395c9b59dc1f35c77a1..aa997f43b8ce37b2b12787d064233bbbb1b9b260 100644
--- a/content/browser/renderer_host/media/video_capture_host.h
+++ b/content/browser/renderer_host/media/video_capture_host.h
@@ -39,6 +39,7 @@
 #include <map>
 
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "base/sequenced_task_runner_helpers.h"
 #include "content/browser/renderer_host/media/video_capture_controller.h"
 #include "content/common/content_export.h"
@@ -97,10 +98,10 @@ class CONTENT_EXPORT VideoCaptureHost
                       const media::VideoCaptureParams& params);
   void OnControllerAdded(
       int device_id, const media::VideoCaptureParams& params,
-      VideoCaptureController* controller);
+      base::WeakPtr<VideoCaptureController> controller);

[Ami GONE FROM CHROMIUM, 2013/09/13 21:17:59]

I guess all these base::WeakPtr<VideoCaptureController>'s are implicitly about
the IO thread, since VCC is so IOthread-ish now.  I just wish there was a way to
annotate them as such in headers.
(nothing actionable for you here unless you can think of a way to effect this
annotation cleverly)

[ncarter (slow), 2013/09/14 00:07:24]

renamed to handler_as_controller. Just kidding; but seriously I know what you
mean. My preferred fix here is actually to stop using the VCC pointer as the
registration token altogether, the whole process by which the VCH/VCC become
mutually aware is kind of weird actually. The old code did a
make_scoped_refptr<> on a bare pointer, so I'm still counting the use of weakptr
here as a slight improvement, is how I sleep at night.

   void DoControllerAddedOnIOThread(
       int device_id, const media::VideoCaptureParams params,
-      VideoCaptureController* controller);
+      base::WeakPtr<VideoCaptureController> controller);
 
   // IPC message: Stop capture on device referenced by |device_id|.
   void OnStopCapture(int device_id);