cc:: Add remote mode to the compositor

cc/trees/remote_proto_channel.h

Index: cc/trees/remote_proto_channel.h
diff --git a/cc/trees/remote_proto_channel.h b/cc/trees/remote_proto_channel.h
index b0f1647e281a8f96e0cf77636a41c62d5267581e..a1bb0b36a5e2a2a7f035aedf957da278812aefde 100644
--- a/cc/trees/remote_proto_channel.h
+++ b/cc/trees/remote_proto_channel.h
@@ -21,6 +21,8 @@ class RemoteProtoChannel {
   // incoming protobufs.
   class ProtoReceiver {
    public:
+    // TODO(khushalsagar): This should probably include a closure that returns
+    // the status of processing this proto.
     virtual void OnProtoReceived(
         scoped_ptr<proto::CompositorMessage> proto) = 0;
 
@@ -28,7 +30,10 @@ class RemoteProtoChannel {
     virtual ~ProtoReceiver() {}
   };
 
+  // Called by the ProtoReceiver. The RemoteProtoChannel must outlive its
+  // receiver.
   virtual void SetProtoReceiver(ProtoReceiver* receiver) = 0;
+
   virtual void SendCompositorProto(const proto::CompositorMessage& proto) = 0;
 
  protected: