Use a direct include of the message_loop header in net/, part 1.

net/dns/serial_worker_unittest.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 "net/dns/serial_worker.h"
 
 #include "base/bind.h"
-#include "base/message_loop.h"
+#include "base/message_loop/message_loop.h"
 #include "base/synchronization/lock.h"
 #include "base/synchronization/waitable_event.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace net {
 
 namespace {
 
 class SerialWorkerTest : public testing::Test {
  public:
@@ skipping 135 matching lines @@
   RunUntilBreak("OnWorkFinished");
 
   // No more tasks should remain.
   message_loop_->AssertIdle();
 }
 
 }  // namespace
 
 }  // namespace net