[Mojo Video Capture] Retire buffers when Android Chromium goes to the background

media/capture/video/video_frame_receiver.h

Index: media/capture/video/video_frame_receiver.h
diff --git a/media/capture/video/video_frame_receiver.h b/media/capture/video/video_frame_receiver.h
index 55d98aa564ae49ca38a8761a9b788bd63810e621..841040ae0c1615219f6df9260b8623081b24c5f4 100644
--- a/media/capture/video/video_frame_receiver.h
+++ b/media/capture/video/video_frame_receiver.h
@@ -21,7 +21,15 @@ class CAPTURE_EXPORT VideoFrameReceiver {
       scoped_refptr<media::VideoFrame> frame) = 0;
   virtual void OnError() = 0;
   virtual void OnLog(const std::string& message) = 0;
-  virtual void OnBufferDestroyed(int buffer_id_to_drop) = 0;
+
+  // Tells the VideoFrameReceiver that the producer is no longer going to use
+  // the buffer with id |buffer_id| for frame delivery. This may be called even
+  // while the receiver is still consuming the buffer from a call to
+  // OnIncomingCapturedVideoFrame(). In that case, it means that the
+  // caller is asking the VideoFrameReceiver to release the buffer
+  // at its earliest convenience.
+  // A producer may reuse a retired |buffer_id| immediately after this call.
+  virtual void OnBufferRetired(int buffer_id) = 0;
 };
 
 }  // namespace media