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..f22e7de9d5f20bf2551b977fedea5f6bf1121679
--- /dev/null
+++ b/cc/trees/remote_proto_channel.h
@@ -0,0 +1,35 @@
+// 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"
+#include "cc/base/cc_export.h"
+
+namespace cc {
+
+namespace proto {
+class CompositorMessage;
+}
+
+// Provides a bridge for getting compositor protobuf messages to/from the
+// outside world.
+class CC_EXPORT 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;

[David Trainor- moved to gerrit, 2015/11/17 00:58:34]

Had to make this a scoped_ptr because it's unclear if the receiver will actually
process the proto on this thread (and if it's a const& allocated on the stack
it'd have to be copied otherwise IIUC).

+  };
+
+  virtual void SetProtoReceiver(ProtoReceiver* receiver) = 0;
+  virtual void SendCompositorProto(const proto::CompositorMessage& proto) = 0;
+};
+
+}  // namespace cc
+
+#endif  // CC_TREES_REMOTE_PROTO_CHANNEL_H_