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

net/base/test_completion_callback_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.
 
 // Illustrates how to use worker threads that issue completion callbacks
 
 #include "base/bind.h"
 #include "base/logging.h"
-#include "base/message_loop.h"
+#include "base/message_loop/message_loop.h"
 #include "base/threading/worker_pool.h"
 #include "net/base/completion_callback.h"
 #include "net/base/test_completion_callback.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/platform_test.h"
 
 typedef PlatformTest TestCompletionCallbackTest;
 
 const int kMagicResult = 8888;
 
@@ skipping 94 matching lines @@
 TEST_F(TestCompletionCallbackTest, Simple) {
   ExampleEmployer boss;
   net::TestCompletionCallback callback;
   bool queued = boss.DoSomething(callback.callback());
   EXPECT_EQ(queued, true);
   int result = callback.WaitForResult();
   EXPECT_EQ(result, kMagicResult);
 }
 
 // TODO: test deleting ExampleEmployer while work outstanding