Add missing IWYU message_loop.h includes.

chrome/browser/devtools/device/usb/android_usb_browsertest.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 <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
 #include <unordered_map>
 #include <utility>
 
 #include "base/location.h"
 #include "base/memory/ptr_util.h"
+#include "base/message_loop/message_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "chrome/browser/devtools/device/adb/mock_adb_server.h"
 #include "chrome/browser/devtools/device/devtools_android_bridge.h"
 #include "chrome/browser/devtools/device/usb/android_usb_device.h"
 #include "chrome/browser/devtools/device/usb/usb_device_provider.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/test/base/in_process_browser_test.h"
 #include "content/public/browser/browser_thread.h"
@@ skipping 744 matching lines @@
   EXPECT_EQ(2, listener.invoked_);
   EXPECT_EQ(listener.invoked_ - 1, scheduler_invoked_);
   EXPECT_TRUE(base::MessageLoop::current()->IsIdleForTesting());
 }
 
 IN_PROC_BROWSER_TEST_F(AndroidUsbTraitsTest, TestDeviceCounting) {
   MockCountListenerForCheckingTraits listener(adb_bridge_);
   adb_bridge_->AddDeviceCountListener(&listener);
   runner_->Run();
 }