cc:: Add remote mode to the compositor

cc/proto/compositor_message_to_impl.proto

Index: cc/proto/compositor_message_to_impl.proto
diff --git a/cc/proto/compositor_message_to_impl.proto b/cc/proto/compositor_message_to_impl.proto
new file mode 100644
index 0000000000000000000000000000000000000000..2faf9056cbf3beae33c5795c52d7e8af80aaad6d
--- /dev/null
+++ b/cc/proto/compositor_message_to_impl.proto
@@ -0,0 +1,28 @@
+// 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.
+
+syntax = "proto2";
+
+option optimize_for = LITE_RUNTIME;
+
+import "layer_tree_settings.proto";
+
+package cc.proto;
+
+// Control messages sent to the impl side of the compositor on the client.
+message CompositorMessageToImpl {
+  enum Type {
+    Unknown = 0;

[vmpstr, 2016/01/07 19:08:11]

I think it's worth documenting each type here with a comment and when it is sent
and what should happen, etc

[Khushal, 2016/01/08 21:17:19]

Done.

+    InitializeImpl = 1;
+    CloseImpl = 2;
+    MainThreadHasStoppedFlingingOnImpl = 3;
+  }
+
+  optional Type message_type = 1;
+  optional InitializeImpl initialize_impl_message = 2;
+}
+
+message InitializeImpl {
+  optional LayerTreeSettings layer_tree_settings = 1;
+}