Update from https://crrev.com/315085

cc/trees/thread_proxy.cc

 // 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.
 
 #include "cc/trees/thread_proxy.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/auto_reset.h"
@@ skipping 778 matching lines @@
   bool can_cancel_this_commit =
       main().can_cancel_commit && !begin_main_frame_state->evicted_ui_resources;
   main().can_cancel_commit = true;
 
   scoped_ptr<ResourceUpdateQueue> queue =
       make_scoped_ptr(new ResourceUpdateQueue);
 
   bool updated = layer_tree_host()->UpdateLayers(queue.get());
 
   layer_tree_host()->WillCommit();
+  devtools_instrumentation::ScopedCommitTrace commit_task(
+      layer_tree_host()->id());
 
   // Before calling animate, we set main().animate_requested to false. If it is
   // true now, it means SetNeedAnimate was called again, but during a state when
   // main().commit_request_sent_to_impl_thread = true. We need to force that
   // call to happen again now so that the commit request is sent to the impl
   // thread.
   if (main().animate_requested) {
     // Forces SetNeedsAnimate to consider posting a commit task.
     main().animate_requested = false;
     SetNeedsAnimate();
@@ skipping 556 matching lines @@
 }
 
 void ThreadProxy::DidCompletePageScaleAnimationOnImplThread() {
   DCHECK(IsImplThread());
   Proxy::MainThreadTaskRunner()->PostTask(
       FROM_HERE, base::Bind(&ThreadProxy::DidCompletePageScaleAnimation,
                             main_thread_weak_ptr_));
 }
 
 }  // namespace cc