Clarify ownership of GpuVideoDecodeAcceleratorHost and avoid crash on context loss.

media/filters/gpu_video_decoder.h

Index: media/filters/gpu_video_decoder.h
diff --git a/media/filters/gpu_video_decoder.h b/media/filters/gpu_video_decoder.h
index af6dcf8d6738f5e55f7fffb3170f276306b0a858..33f71c044f2d9b176d1ebd6d50fcd25b8b056ec1 100644
--- a/media/filters/gpu_video_decoder.h
+++ b/media/filters/gpu_video_decoder.h
@@ -125,6 +125,10 @@ class MEDIA_EXPORT GpuVideoDecoder
   // thread).
   void SetVDA(VideoDecodeAccelerator* vda);
 
+  // Call VDA::Destroy() on |vda_loop_proxy_| ensuring that |this| outlives the
+  // Destroy() call.
+  void DestroyVDA();
+
   // A shared memory segment and its allocated size.
   struct SHMBuffer {
     SHMBuffer(base::SharedMemory* m, size_t s);