Add IPC messages to transfer compositor protos

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
new file mode 100644
index 0000000000000000000000000000000000000000..b0f1647e281a8f96e0cf77636a41c62d5267581e
--- /dev/null
+++ b/cc/trees/remote_proto_channel.h
@@ -0,0 +1,40 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CC_TREES_REMOTE_PROTO_CHANNEL_H_
+#define CC_TREES_REMOTE_PROTO_CHANNEL_H_
+
+#include "base/memory/scoped_ptr.h"
+
+namespace cc {
+
+namespace proto {
+class CompositorMessage;
+}
+
+// Provides a bridge for getting compositor protobuf messages to/from the
+// outside world.
+class RemoteProtoChannel {
+ public:
+  // Meant to be implemented by a RemoteChannel that needs to receive and parse
+  // incoming protobufs.
+  class ProtoReceiver {
+   public:
+    virtual void OnProtoReceived(
+        scoped_ptr<proto::CompositorMessage> proto) = 0;
+
+   protected:
+    virtual ~ProtoReceiver() {}
+  };
+
+  virtual void SetProtoReceiver(ProtoReceiver* receiver) = 0;
+  virtual void SendCompositorProto(const proto::CompositorMessage& proto) = 0;
+
+ protected:
+  virtual ~RemoteProtoChannel() {}
+};
+
+}  // namespace cc
+
+#endif  // CC_TREES_REMOTE_PROTO_CHANNEL_H_