exo: CompositorFrameSink code cleanup.

Update comments to reflect latest code and remove unncessary
function and if-statements.

BUG=675004

Review-Url: https://codereview.chromium.org/2625153002
Cr-Commit-Position: refs/heads/master@{#442998}

components/exo/buffer.h

@@ -104,29 +104,28 @@ class Buffer : public base::SupportsWeakPtr<Buffer> {
   // True if this buffer is an overlay candidate.
   const bool is_overlay_candidate_;
 
-  // This is incremented when a texture mailbox is produced and decremented
-  // when a texture mailbox is released. It is used to determine when we should
-  // notify the client that buffer has been released.
+  // This is incremented when a transferable resource is produced and
+  // decremented when a transferable resource is released. It is used to
+  // determine when we should notify the client that buffer has been released.
   unsigned use_count_ = 0;
 
   // This keeps track of how many Surfaces the buffer is attached to.
   unsigned attach_count_ = 0;
 
-  // The last used texture. ProduceTextureMailbox() will use this
+  // The last used texture. ProduceTransferableResource() will use this
   // instead of creating a new texture when possible.
   std::unique_ptr<Texture> texture_;
 
-  // The last used contents texture. ProduceTextureMailbox() will use this
+  // The last used contents texture. ProduceTransferableResource() will use this
   // instead of creating a new texture when possible.
   std::unique_ptr<Texture> contents_texture_;
 
   // The client release callback.
   base::Closure release_callback_;
 
-  // The CompositorFrameSinkHolder that has the ReleaseCallback of this buffer
-  // produced in ProduceTextureMailbox().
-  // Buffer holds a reference to the CompositorFrameSinkHolder to keep it alive.
-  // The refptr is reset when the release callback is called.
+  // CompositorFrameSinkHolder instance that needs to be kept alive to receive
+  // a release callback when the last produced transferable resource is no
+  // longer in use.
   scoped_refptr<CompositorFrameSinkHolder> compositor_frame_sink_holder_;
 
   DISALLOW_COPY_AND_ASSIGN(Buffer);

components/exo/compositor_frame_sink.cc

@@ -14,20 +14,6 @@ namespace exo {
 ////////////////////////////////////////////////////////////////////////////////
 // ExoComopositorFrameSink, public:
 
-// static
-void CompositorFrameSink::Create(
-    const cc::FrameSinkId& frame_sink_id,
-    cc::SurfaceManager* surface_manager,
-    cc::mojom::MojoCompositorFrameSinkClientPtr client,
-    cc::mojom::MojoCompositorFrameSinkRequest request) {
-  std::unique_ptr<CompositorFrameSink> impl =
-      base::MakeUnique<CompositorFrameSink>(frame_sink_id, surface_manager,
-                                            std::move(client));
-  CompositorFrameSink* compositor_frame_sink = impl.get();
-  compositor_frame_sink->binding_ =
-      mojo::MakeStrongBinding(std::move(impl), std::move(request));
-}
-
 CompositorFrameSink::CompositorFrameSink(
     const cc::FrameSinkId& frame_sink_id,
     cc::SurfaceManager* surface_manager,
@@ -79,24 +65,20 @@ void CompositorFrameSink::Satisfy(const cc::SurfaceSequence& sequence) {
 // cc::CompositorFrameSinkSupportClient overrides:
 
 void CompositorFrameSink::DidReceiveCompositorFrameAck() {
-  if (client_)
-    client_->DidReceiveCompositorFrameAck();
+  client_->DidReceiveCompositorFrameAck();
 }
 
 void CompositorFrameSink::OnBeginFrame(const cc::BeginFrameArgs& args) {
-  if (client_)
-    client_->OnBeginFrame(args);
+  client_->OnBeginFrame(args);
 }
 
 void CompositorFrameSink::ReclaimResources(
     const cc::ReturnedResourceArray& resources) {
-  if (client_)
-    client_->ReclaimResources(resources);
+  client_->ReclaimResources(resources);
 }
 
 void CompositorFrameSink::WillDrawSurface() {
-  if (client_)
-    client_->WillDrawSurface();
+  client_->WillDrawSurface();
 }
 
 }  // namespace exo

components/exo/compositor_frame_sink.h

@@ -17,11 +17,6 @@ namespace exo {
 class CompositorFrameSink : public cc::CompositorFrameSinkSupportClient,
                             public cc::mojom::MojoCompositorFrameSink {
  public:
-  static void Create(const cc::FrameSinkId& frame_sink_id,
-                     cc::SurfaceManager* surface_manager,
-                     cc::mojom::MojoCompositorFrameSinkClientPtr client,
-                     cc::mojom::MojoCompositorFrameSinkRequest request);
-
   CompositorFrameSink(const cc::FrameSinkId& frame_sink_id,
                       cc::SurfaceManager* surface_manager,
                       cc::mojom::MojoCompositorFrameSinkClientPtr client);