Aura Window Capture: Ensure capture callback is always run.

content/browser/media/capture/aura_window_capture_machine.h

Index: content/browser/media/capture/aura_window_capture_machine.h
diff --git a/content/browser/media/capture/aura_window_capture_machine.h b/content/browser/media/capture/aura_window_capture_machine.h
index 70aad807b8023eedf0756f280a858698f384315a..25ced7a47a4c80617904beb78ed68fedc5261b05 100644
--- a/content/browser/media/capture/aura_window_capture_machine.h
+++ b/content/browser/media/capture/aura_window_capture_machine.h
@@ -86,7 +86,9 @@ class AuraWindowCaptureMachine
                      std::unique_ptr<cc::CopyOutputResult> result);
 
   // A helper which does the real work for DidCopyOutput. Returns true if
-  // succeeded.
+  // succeeded and |capture_frame_cb| will be run at some future point. Returns
+  // false on error, and |capture_frame_cb| should be run by the caller (with
+  // failure status).
   bool ProcessCopyOutputResponse(scoped_refptr<media::VideoFrame> video_frame,
                                  base::TimeTicks start_time,
                                  const CaptureFrameCallback& capture_frame_cb,