Add missing IWYU message_loop.h includes.

android_webview/browser/test/rendering_test.cc

 // Copyright 2014 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 "android_webview/browser/test/rendering_test.h"
 
 #include <utility>
 
 #include "android_webview/browser/browser_view_renderer.h"
 #include "android_webview/browser/child_frame.h"
 #include "android_webview/browser/render_thread_manager.h"
 #include "android_webview/common/aw_switches.h"
 #include "base/command_line.h"
 #include "base/location.h"
 #include "base/memory/ptr_util.h"
+#include "base/message_loop/message_loop.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "cc/output/compositor_frame.h"
 #include "content/public/browser/android/synchronous_compositor.h"
 #include "content/public/test/test_synchronous_compositor_android.h"
 
 namespace android_webview {
 
 namespace {
 // BrowserViewRenderer subclass used for enabling tests to observe
 // OnParentDrawConstraintsUpdated.
@@ skipping 132 matching lines @@
 void RenderingTest::PostInvalidate() {
   if (window_)
     window_->PostInvalidate();
 }
 
 gfx::Point RenderingTest::GetLocationOnScreen() {
   return gfx::Point();
 }
 
 }  // namespace android_webview