Fix CompositorCC initialization/shutdown

ui/gfx/compositor/compositor_cc.cc

 // Copyright (c) 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 "ui/gfx/compositor/compositor_cc.h"
 
 #include "base/command_line.h"
 #include "third_party/skia/include/images/SkImageEncoder.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebCompositor.h"
@@ skipping 148 matching lines @@
 #else
   if (use_thread)
     WebKit::WebCompositor::setThread(g_compositor_thread);
 #endif
 }
 
 void CompositorCC::Terminate() {
 #ifdef WEBCOMPOSITOR_HAS_INITIALIZE
   WebKit::WebCompositor::shutdown();
 #endif
-  DCHECK(g_compositor_thread);
-  delete g_compositor_thread;
-  g_compositor_thread = NULL;
+  if (g_compositor_thread) {
+    delete g_compositor_thread;
+    g_compositor_thread = NULL;
+  }
 }
 
 // static
 void CompositorCC::EnableTestContextIfNecessary() {
   // TODO: only do this if command line param not set.
   test_context_enabled_ = true;
 }
 
 Texture* CompositorCC::CreateTexture() {
   NOTREACHED();
@@ skipping 97 matching lines @@
   ScheduleDraw();
 }
 
 Compositor* Compositor::Create(CompositorDelegate* owner,
                                gfx::AcceleratedWidget widget,
                                const gfx::Size& size) {
   return new CompositorCC(owner, widget, size);
 }
 
 }  // namespace ui