cc:: Add remote mode to the compositor

cc/trees/compositor_mode.h

 // 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_COMPOSITOR_MODE_H_
 #define CC_TREES_COMPOSITOR_MODE_H_
 
 namespace cc {
 
 // The LayerTreeHost uses the CompositorMode to determine the current mode of
 // operation, which is needed to:
 // 1) Safely cast Proxy to SingleThreadProxy to allow operations only supported
 // in SingleThreaded mode.
 // 2) Make decisions restricted to either browser(SingleThreaded) or renderer
-// compositors(Threaded).
-enum CompositorMode {
-  SingleThreaded,
-  Threaded,
+// compositors(Threaded/Remote).
+enum class CompositorMode {
+  // The main and impl components will be run on the same thread.
+  SINGLE_THREADED,
+
+  // The main and impl components be run on different threads.
+  THREADED,
+
+  // The main and impl components will be run across the network.
+  REMOTE,
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_COMPOSITOR_MODE_H_