Use a direct include of the message_loop header in ppapi/, printing/, rlz/, sync/.

sync/test/accounts_client/test_accounts_client.h

 // Copyright 2013 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.
 
 #ifndef SYNC_TEST_ACCOUNTS_CLIENT_TEST_ACCOUNTS_CLIENT_H_
 #define SYNC_TEST_ACCOUNTS_CLIENT_TEST_ACCOUNTS_CLIENT_H_
 
 #include <string>
 #include <vector>
 
-#include "base/message_loop.h"
+#include "base/message_loop/message_loop.h"
 #include "url/gurl.h"
 
 using std::string;
 using std::vector;
 
 // The data associated with an account session.
 struct AccountSession {
   AccountSession();
   ~AccountSession();
 
@@ skipping 32 matching lines @@
 
  private:
   GURL CreateGURLWithPath(const string& path);
   base::MessageLoopForIO io_loop_;
   const string server_;
   const string account_space_;
   vector<string> usernames_;
 };
 
 #endif  // SYNC_TEST_ACCOUNTS_CLIENT_TEST_ACCOUNTS_CLIENT_H_