Remove unused thread.h include in trace_event_impl.h and fix IWUU.

ui/gl/gl_context_cgl.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 "ui/gl/gl_context_cgl.h"
 
 #include <OpenGL/CGLRenderers.h>
 #include <OpenGL/CGLTypes.h>
 
 #include <memory>
 #include <vector>
 
 #include "base/location.h"
 #include "base/logging.h"
+#include "base/message_loop/message_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/trace_event/trace_event.h"
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_implementation.h"
 #include "ui/gl/gl_surface.h"
 #include "ui/gl/gpu_switching_manager.h"
 #include "ui/gl/scoped_cgl.h"
 #include "ui/gl/yuv_to_rgb_converter.h"
 
@@ skipping 255 matching lines @@
 
 GLContextCGL::~GLContextCGL() {
   Destroy();
 }
 
 GpuPreference GLContextCGL::GetGpuPreference() {
   return gpu_preference_;
 }
 
 }  // namespace gl