Use a direct include of the message_loop header in base/.

base/message_loop/message_pump_io_ios_unittest.cc

 // Copyright 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 "base/message_loop/message_pump_io_ios.h"
 
 #include <unistd.h>
 
-#include "base/message_loop.h"
+#include "base/message_loop/message_loop.h"
 #include "base/posix/eintr_wrapper.h"
 #include "base/threading/thread.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
 
 class MessagePumpIOSForIOTest : public testing::Test {
  protected:
   MessagePumpIOSForIOTest()
       : ui_loop_(MessageLoop::TYPE_UI),
@@ skipping 159 matching lines @@
   pump->WatchFileDescriptor(pipefds_[1],
       false, MessagePumpIOSForIO::WATCH_READ_WRITE, &watcher, &delegate);
 
   // Spoof a callback.
   HandleFdIOEvent(&watcher);
 }
 
 }  // namespace
 
 }  // namespace base