Bug fix: stop mirroring session when tab is closed.

content/renderer/media/media_stream_video_capturer_source.cc

Index: content/renderer/media/media_stream_video_capturer_source.cc
diff --git a/content/renderer/media/media_stream_video_capturer_source.cc b/content/renderer/media/media_stream_video_capturer_source.cc
index b04383dbee35ef5b385cf36e076df458d8832aa2..2ee2b7894167af788ae37cc91f6d5ab26218d42e 100644
--- a/content/renderer/media/media_stream_video_capturer_source.cc
+++ b/content/renderer/media/media_stream_video_capturer_source.cc
@@ -233,11 +233,8 @@ class LocalVideoCapturerSource final : public media::VideoCapturerSource {
   // Indicates if we are capturing generated content, e.g. Tab or Desktop.
   const bool is_content_capture_;
 
-  // This is run once to report whether the device was successfully started
-  // after a call to StartCapture().
+  // These two are valid between StartCapture() and StopCapture().
   RunningCallback running_callback_;

[mcasas, 2016/10/13 13:48:43]

nit: the name is misleading, maybe we could
call if 
StateUpdateCB state_update_callback_; ,
or
IsRunningCallback is_running_callback_;
Doesn't feel entirely right though... I'll be OK
with whatever you do.

[xjz, 2016/10/13 18:11:39]

Yes, the name sounds a little confusing. But it seems that currently only this
LocalVideoCapturerSource uses this callback to notify that when capture stops or
error happens. For other VideoCapturerSource, this callback is just used as a
StartCapture callback. I don't have a better idea for this naming issue. So keep
it as is for now, and add a comment here to explain when it will be called.

-
-  // This is valid between StartCapture() and StopCapture().
   base::Closure stop_capture_cb_;
 
   // Placeholder keeping the callback between asynchronous device enumeration
@@ -355,7 +352,7 @@ void LocalVideoCapturerSource::OnStateUpdate(VideoCaptureState state) {
     return;
   switch (state) {
     case VIDEO_CAPTURE_STATE_STARTED:
-      base::ResetAndReturn(&running_callback_).Run(true);
+      running_callback_.Run(true);
       break;
 
     case VIDEO_CAPTURE_STATE_STOPPING: