Use a direct include of the message_loop header in content/, part 3.

content/public/test/test_navigation_observer.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 "content/public/test/test_navigation_observer.h"
 
 #include "base/bind.h"
-#include "base/message_loop.h"
+#include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/stl_util.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/test/test_utils.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace content {
 
@@ skipping 139 matching lines @@
 }
 
 void TestNavigationObserver::OnNavigationEntryCommitted(
     TestWebContentsObserver* observer,
     WebContents* web_contents,
     const LoadCommittedDetails& load_details) {
   navigation_started_ = true;
 }
 
 }  // namespace content