Add missing IWYU message_loop.h includes.

chrome/browser/geolocation/geolocation_browsertest.cc

 // Copyright (c) 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 <stddef.h>
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
+#include "base/message_loop/message_loop.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/simple_test_clock.h"
 #include "base/time/clock.h"
 #include "build/build_config.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/content_settings/host_content_settings_map_factory.h"
 #include "chrome/browser/content_settings/tab_specific_content_settings.h"
 #include "chrome/browser/permissions/permission_request_manager.h"
@@ skipping 716 matching lines @@
   ASSERT_NO_FATAL_FAILURE(Initialize(INITIALIZATION_DEFAULT));
   WatchPositionAndObservePermissionRequest(true);
 
   // TODO(mvanouwerkerk): Can't close a window you did not open. Maybe this was
   // valid when the test was written, but now it just prints "Scripts may close
   // only the windows that were opened by it."
   std::string script = "window.domAutomationController.send(window.close())";
   ASSERT_TRUE(content::ExecuteScript(
       current_browser()->tab_strip_model()->GetActiveWebContents(), script));
 }