[Chromecast] Make sure that Stop() stops buffer decryption

chromecast/media/cma/pipeline/av_pipeline_impl.h

Index: chromecast/media/cma/pipeline/av_pipeline_impl.h
diff --git a/chromecast/media/cma/pipeline/av_pipeline_impl.h b/chromecast/media/cma/pipeline/av_pipeline_impl.h
index d8f752263a8781913d167acdc209e8cef5d72248..b9293b94318e228027ba7b1e684ec16950386bda 100644
--- a/chromecast/media/cma/pipeline/av_pipeline_impl.h
+++ b/chromecast/media/cma/pipeline/av_pipeline_impl.h
@@ -172,6 +172,10 @@ class AvPipelineImpl : MediaPipelineBackend::Decoder::Delegate {
 
   base::WeakPtr<AvPipelineImpl> weak_this_;
   base::WeakPtrFactory<AvPipelineImpl> weak_factory_;
+  // Special weak factory used for asynchronous decryption. This allows us to
+  // cancel pending asynchronous decryption (by invalidating this factory's weak
+  // ptrs) without affecting other bound callbacks.
+  base::WeakPtrFactory<AvPipelineImpl> decrypt_weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AvPipelineImpl);
 };