Begin adding support for tab mirroring via the MediaStream audio/video capturing

content/browser/renderer_host/media/video_capture_host.cc

Index: content/browser/renderer_host/media/video_capture_host.cc
diff --git a/content/browser/renderer_host/media/video_capture_host.cc b/content/browser/renderer_host/media/video_capture_host.cc
index 4bf69f1442d8ce254e1a577913de938b25409f50..500e19fb77e7eaf6e0ddf0f6fa210ed1dd58d929 100644
--- a/content/browser/renderer_host/media/video_capture_host.cc
+++ b/content/browser/renderer_host/media/video_capture_host.cc
@@ -11,6 +11,7 @@
 #include "content/browser/renderer_host/media/media_stream_manager.h"
 #include "content/browser/renderer_host/media/video_capture_manager.h"
 #include "content/common/media/video_capture_messages.h"
+#include "content/public/common/media_stream_request.h"
 
 using content::BrowserMainLoop;
 using content::BrowserMessageFilter;
@@ -279,5 +280,9 @@ void VideoCaptureHost::DeleteVideoCaptureControllerOnIOThread(
 
 media_stream::VideoCaptureManager* VideoCaptureHost::GetVideoCaptureManager() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  return BrowserMainLoop::GetMediaStreamManager()->video_capture_manager();
+  // TODO(miu): Confirm use of VideoCaptureHostMsg_* only applies to the user
+  // video capture devices, and does not have anything to do with
+  // MediaStreamHostMsg_*.
+  return BrowserMainLoop::GetMediaStreamManager()->GetVideoCaptureManager(
+      content::MEDIA_USER_VIDEO_CAPTURE);
 }