Attempt four at landing the "histogram.h removed from message_loop.h" patch.

chrome/browser/chrome_thread_unittest.cc

 // Copyright (c) 2010 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 "base/message_loop.h"
 #include "base/message_loop_proxy.h"
+#include "base/scoped_ptr.h"
 #include "chrome/browser/chrome_thread.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/platform_test.h"
 
 class ChromeThreadTest : public testing::Test {
  public:
   void Release() {
     CHECK(ChromeThread::CurrentlyOn(ChromeThread::UI));
     loop_.PostTask(FROM_HERE, new MessageLoop::QuitTask);
   }
@@ skipping 137 matching lines @@
     io_thread->Start();
   }
   bool deleted = false;
   scoped_refptr<base::MessageLoopProxy> message_loop_proxy =
       ChromeThread::GetMessageLoopProxyForThread(ChromeThread::IO);
   bool ret = message_loop_proxy->PostTask(FROM_HERE, new DummyTask(&deleted));
   EXPECT_FALSE(ret);
   EXPECT_TRUE(deleted);
 }