Reduce header dependencies in base/

base/tracked_objects_unittest.cc

 // Copyright (c) 2006-2008 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.
 
 // Test of classes in the tracked_objects.h classes.
 
 #include "base/tracked_objects.h"
+
+#include "base/message_loop.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace tracked_objects {
 
 class TrackedObjectsTest : public testing::Test {
  public:
   MessageLoop message_loop_;
 };
 
 TEST_F(TrackedObjectsTest, MinimalStartupShutdown) {
@@ skipping 67 matching lines @@
   EXPECT_EQ(1u, death_map.size());                         // 1 location.
   EXPECT_EQ(1, death_map.begin()->second.count());         // 1 death.
 
   // The births were at the same location as the one known death.
   EXPECT_EQ(birth_map.begin()->second, death_map.begin()->first);
 
   ThreadData::ShutdownSingleThreadedCleanup();
 }
 
 }  // namespace tracked_objects