Adding shutdown tracing capabilities

ui/compositor/compositor.cc

 // Copyright (c) 2012 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 "ui/compositor/compositor.h"
 
 #include <algorithm>
 #include <deque>
 
 #include "base/bind.h"
 #include "base/command_line.h"
+#include "base/debug/trace_event.h"
 #include "base/memory/singleton.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/strings/string_util.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_restrictions.h"
 #include "cc/base/switches.h"
 #include "cc/debug/test_context_provider.h"
 #include "cc/debug/test_web_graphics_context_3d.h"
 #include "cc/input/input_handler.h"
@@ skipping 389 matching lines @@
 
   scoped_refptr<base::SingleThreadTaskRunner> compositor_task_runner =
       g_compositor_thread ? g_compositor_thread->message_loop_proxy() : NULL;
 
   host_ = cc::LayerTreeHost::Create(this, settings, compositor_task_runner);
   host_->SetRootLayer(root_web_layer_);
   host_->SetLayerTreeHostClientReady();
 }
 
 Compositor::~Compositor() {
+  TRACE_EVENT0("shutdown", "Compositor::destructor");
+
   DCHECK(g_compositor_initialized);
 
   CancelCompositorLock();
   DCHECK(!compositor_lock_);
 
   // Don't call |CompositorDelegate::ScheduleDraw| from this point.
   delegate_ = NULL;
   if (root_layer_)
     root_layer_->SetCompositor(NULL);
 
@@ skipping 333 matching lines @@
 }
 
 void Compositor::NotifyEnd() {
   last_ended_frame_++;
   FOR_EACH_OBSERVER(CompositorObserver,
                     observer_list_,
                     OnCompositingEnded(this));
 }
 
 }  // namespace ui