cc: Use const ref to avoid extra ref count of VideoProviderClientImpl.

cc/layers/video_layer_impl.h

Index: cc/layers/video_layer_impl.h
diff --git a/cc/layers/video_layer_impl.h b/cc/layers/video_layer_impl.h
index 5e99923b1278f4bd61507cc663fca2459253d16a..0a617985b4d8f29482fe6de3ee15ee384c85d710 100644
--- a/cc/layers/video_layer_impl.h
+++ b/cc/layers/video_layer_impl.h
@@ -48,7 +48,7 @@ class CC_EXPORT VideoLayerImpl : public LayerImpl {
   VideoLayerImpl(
       LayerTreeImpl* tree_impl,
       int id,
-      scoped_refptr<VideoFrameProviderClientImpl> provider_client_impl,
+      const scoped_refptr<VideoFrameProviderClientImpl>& provider_client_impl,
       media::VideoRotation video_rotation);
 
   const char* LayerTypeAsString() const override;