Aura Window Capture: Ensure capture callback is always run.

media/capture/content/thread_safe_capture_oracle.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_CAPTURE_CONTENT_THREAD_SAFE_CAPTURE_ORACLE_H_
 #define MEDIA_CAPTURE_CONTENT_THREAD_SAFE_CAPTURE_ORACLE_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 30 matching lines @@
   typedef base::Callback<void(const scoped_refptr<VideoFrame>& frame,
                               base::TimeTicks timestamp,
                               bool success)> CaptureFrameCallback;
 
   // Record a change |event| along with its |damage_rect| and |event_time|, and
   // then make a decision whether to proceed with capture. The decision is based
   // on recent event history, capture activity, and the availability of
   // resources.
   //
   // If this method returns false, the caller should take no further action.
-  // Otherwise, |storage| is set to the destination for the video frame capture;
-  // and, the caller should initiate capture, and then run |callback| once the
-  // video frame has been populated with its content.
+  // Otherwise, |storage| is set to the destination for the video frame capture
+  // and the caller should initiate capture.  Then, once the video frame has
+  // been populated with its content, or if capture failed, the |callback|
+  // should be run.
   bool ObserveEventAndDecideCapture(VideoCaptureOracle::Event event,
                                     const gfx::Rect& damage_rect,
                                     base::TimeTicks event_time,
                                     scoped_refptr<VideoFrame>* storage,
                                     CaptureFrameCallback* callback);
 
   // Attempt to re-send the last frame to the VideoCaptureDevice::Client.
   // Returns true if successful. This can fail if the last frame is no longer
   // available in the buffer pool, or if the VideoCaptureOracle decides to
   // reject the "passive" refresh.
@@ skipping 53 matching lines @@
   // Makes the decision to capture a frame.
   VideoCaptureOracle oracle_;
 
   // The video capture parameters used to construct the oracle proxy.
   const VideoCaptureParams params_;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_CAPTURE_CONTENT_THREAD_SAFE_CAPTURE_ORACLE_H_