Add a |scope| argument to TRACE_EVENT_INSTANT* and require its presence.

cc/layer_tree_host.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/layer_tree_host.h"
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/message_loop.h"
 #include "base/stl_util.h"
@@ skipping 407 matching lines @@
 
 void LayerTreeHost::setNeedsAnimate()
 {
     DCHECK(m_proxy->hasImplThread());
     m_proxy->setNeedsAnimate();
 }
 
 void LayerTreeHost::setNeedsCommit()
 {
     if (!m_prepaintCallback.IsCancelled()) {
-        TRACE_EVENT_INSTANT0("cc", "LayerTreeHost::setNeedsCommit::cancel prepaint");
+        TRACE_EVENT_INSTANT0("cc", "LayerTreeHost::setNeedsCommit::cancel prepaint",
+                             TRACE_EVENT_SCOPE_THREAD);
         m_prepaintCallback.Cancel();
     }
     m_proxy->setNeedsCommit();
 }
 
 void LayerTreeHost::setNeedsFullTreeSync()
 {
     m_needsFullTreeSync = true;
     setNeedsCommit();
 }
@@ skipping 438 matching lines @@
     for (size_t childIndex = 0; childIndex < layer->children().size(); ++childIndex)
         setAnimationEventsRecursive(events, layer->children()[childIndex].get(), wallClockTime);
 }
 
 skia::RefPtr<SkPicture> LayerTreeHost::capturePicture()
 {
     return m_proxy->capturePicture();
 }
 
 }  // namespace cc