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

media/capture/video/video_capture_buffer_pool_impl.h

Index: media/capture/video/video_capture_buffer_pool_impl.h
diff --git a/media/capture/video/video_capture_buffer_pool_impl.h b/media/capture/video/video_capture_buffer_pool_impl.h
index b5073df7d742ce986effddcfb35ddfce42050e91..ab6cd518eb98330ba9783e47cd5e8bd1819b7cc3 100644
--- a/media/capture/video/video_capture_buffer_pool_impl.h
+++ b/media/capture/video/video_capture_buffer_pool_impl.h
@@ -27,6 +27,9 @@
 
 namespace media {
 
+// This implementation guarantees that, even when creating new instances,
+// a previously used |buffer_id| is never reused without first cycling through
+// the complete int range.
 class CAPTURE_EXPORT VideoCaptureBufferPoolImpl
     : public VideoCaptureBufferPool {
  public:
@@ -73,7 +76,7 @@ class CAPTURE_EXPORT VideoCaptureBufferPoolImpl
   mutable base::Lock lock_;
 
   // The ID of the next buffer.
-  int next_buffer_id_;
+  static int next_buffer_id_;
 
   // The ID of the buffer last relinquished by the producer (a candidate for
   // resurrection).