cc: add DevTools instrumentation for impl-side frames

cc/trees/thread_proxy.h

 // Copyright 2011 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_THREAD_PROXY_H_
 #define CC_TREES_THREAD_PROXY_H_
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 271 matching lines @@
   // Used for computing samples added to
   // begin_main_frame_to_commit_duration_history_ and
   // activation_duration_history_.
   base::TimeTicks begin_main_frame_sent_time_;
   base::TimeTicks commit_complete_time_;
 
   base::WeakPtr<ThreadProxy> main_thread_weak_ptr_;
   base::WeakPtrFactory<ThreadProxy> weak_factory_on_impl_thread_;
   base::WeakPtrFactory<ThreadProxy> weak_factory_;
 
+  const int layer_tree_host_id_;
+
   DISALLOW_COPY_AND_ASSIGN(ThreadProxy);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_THREAD_PROXY_H_