Adding shutdown tracing capabilities

ui/aura/root_window.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/aura/root_window.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 152 matching lines @@
   compositor_.reset(new ui::Compositor(this, host_->GetAcceleratedWidget()));
   DCHECK(compositor_.get());
   compositor_->AddObserver(this);
 
   prop_.reset(new ui::ViewProp(host_->GetAcceleratedWidget(),
                                kRootWindowForAcceleratedWidget,
                                this));
 }
 
 RootWindow::~RootWindow() {
+  TRACE_EVENT0("shutdown", "RootWindow::Destructor");
+
   compositor_->RemoveObserver(this);
   // Make sure to destroy the compositor before terminating so that state is
   // cleared and we don't hit asserts.
   compositor_.reset();
 
   // Tear down in reverse.  Frees any references held by the host.
   host_.reset(NULL);
 
   // An observer may have been added by an animation on the RootWindow.
   layer()->GetAnimator()->RemoveObserver(this);
@@ skipping 1057 matching lines @@
 }
 
 gfx::Transform RootWindow::GetInverseRootTransform() const {
   float scale = ui::GetDeviceScaleFactor(layer());
   gfx::Transform transform;
   transform.Scale(1.0f / scale, 1.0f / scale);
   return transformer_->GetInverseTransform() * transform;
 }
 
 }  // namespace aura