cc: Various code safety improvements in video compositing code.

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 d05bd5768e62f57c6d2773880397df7c671ef68b..5e99923b1278f4bd61507cc663fca2459253d16a 100644
--- a/cc/layers/video_layer_impl.h
+++ b/cc/layers/video_layer_impl.h
@@ -23,6 +23,8 @@ class VideoFrameProviderClientImpl;
 
 class CC_EXPORT VideoLayerImpl : public LayerImpl {
  public:
+  // Must be called on the impl thread while the main thread is blocked. This is
+  // so that |provider| stays alive while this is being created.
   static scoped_ptr<VideoLayerImpl> Create(LayerTreeImpl* tree_impl,
                                            int id,
                                            VideoFrameProvider* provider,
@@ -31,7 +33,6 @@ class CC_EXPORT VideoLayerImpl : public LayerImpl {
 
   // LayerImpl implementation.
   scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl) override;
-  void PushPropertiesTo(LayerImpl* layer) override;
   bool WillDraw(DrawMode draw_mode,
                 ResourceProvider* resource_provider) override;
   void AppendQuads(RenderPass* render_pass,
@@ -41,16 +42,14 @@ class CC_EXPORT VideoLayerImpl : public LayerImpl {
   void ReleaseResources() override;
 
   void SetNeedsRedraw();
-
-  void SetProviderClientImpl(
-      scoped_refptr<VideoFrameProviderClientImpl> provider_client_impl);
-
   media::VideoRotation video_rotation() const { return video_rotation_; }
 
  private:
-  VideoLayerImpl(LayerTreeImpl* tree_impl,
-                 int id,
-                 media::VideoRotation video_rotation);
+  VideoLayerImpl(
+      LayerTreeImpl* tree_impl,
+      int id,
+      scoped_refptr<VideoFrameProviderClientImpl> provider_client_impl,

[DaleCurtis, 2015/03/27 16:45:07]

I realize this is just copying existing style, but this should really be a
const& to avoid extra potential ref/unref steps (which if RefCountedThreadSafe
are atomic operations).

[danakj, 2015/03/27 16:55:15]

I guess, this happens once per video being loaded, I think that it won't matter.
A const& would be fine, or alternatively, we can swap() it into the member
variable in the constructor.

We should really get r-value reference support for scoped_refptr so we can do
this properly with a Pass() or the like.

[DaleCurtis, 2015/03/27 19:53:26]

Yeah, it's not really an issue in this case, just one of those in aggregate
style things.

+      media::VideoRotation video_rotation);
 
   const char* LayerTypeAsString() const override;