Fix the MessageLoop type in case more than one ozone platform is built

services/ui/gpu/gpu_main.cc

 // Copyright 2016 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 "services/ui/gpu/gpu_main.h"
 
 #include "base/command_line.h"
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
 #include "gpu/ipc/common/gpu_memory_buffer_support.h"
 #include "gpu/ipc/gpu_in_process_thread_service.h"
 #include "gpu/ipc/service/gpu_memory_buffer_factory.h"
 #include "gpu/ipc/service/gpu_watchdog_thread.h"
 #include "services/ui/common/server_gpu_memory_buffer_manager.h"
 #include "services/ui/gpu/gpu_service.h"
 
+#if defined(USE_OZONE)
+#include "ui/ozone/public/ozone_platform.h"
+#endif
+
 #if defined(OS_MACOSX)
 #include "base/message_loop/message_pump_mac.h"
 #endif
 
 namespace {
 
 #if defined(USE_X11)
 std::unique_ptr<base::MessagePump> CreateMessagePumpX11() {
   // TODO(sad): This should create a TYPE_UI message pump, and create a
   // PlatformEventSource when gpu process split happens.
@@ skipping 17 matching lines @@
       io_thread_("GpuIOThread"),
       compositor_thread_("DisplayCompositorThread"),
       binding_(this, std::move(request)) {
   base::Thread::Options thread_options;
 
 #if defined(OS_WIN)
   thread_options.message_loop_type = base::MessageLoop::TYPE_DEFAULT;
 #elif defined(USE_X11)
   thread_options.message_pump_factory = base::Bind(&CreateMessagePumpX11);
 #elif defined(USE_OZONE)
-  thread_options.message_loop_type = base::MessageLoop::TYPE_UI;
+  // Create the OzonePlatform instance without doing any initialization.
+  // The MessageLoop type required depends on the Ozone platform selected at
+  // runtime.
+  ui::OzonePlatform::CreateInstance();

[sadrul, 2017/02/08 01:49:26]

We should not have this here.

[tonikitoo, 2017/02/08 02:42:34]

It was originally suggested by kyle in
https://codereview.chromium.org/2629983002/diff/60001/ui/ozone/public/ozone_p...,
and allows us to create a OzonePlatform instance without doing any
initialization, so that we can make method calls, like
::GetMessageLoopTypeForGpu

Quoting kyle, "We can't run OzonePlatform::InitializeForGPU()
before the main MessageLoop is created. Something will try and use the
MessageLoop then crash."

However, for mus today still we can call ::GetMessageLoopTypeForGpu without
calling ::CreateInstance. My understanding is that it only works because
mus-ui/mus-gpu process split has not happened yet.
I will leave up a comment with a FIXME, but the previous call to
::CreateInstance would be no-op here.

+  thread_options.message_loop_type =
+      ui::OzonePlatform::GetInstance()->GetMessageLoopTypeForGpu();
 #elif defined(OS_LINUX)
   thread_options.message_loop_type = base::MessageLoop::TYPE_DEFAULT;
 #elif defined(OS_MACOSX)
   thread_options.message_pump_factory = base::Bind(&CreateMessagePumpMac);
 #else
   thread_options.message_loop_type = base::MessageLoop::TYPE_IO;
 #endif
 
 #if defined(OS_ANDROID) || defined(OS_CHROMEOS)
   thread_options.priority = base::ThreadPriority::DISPLAY;
@@ skipping 173 matching lines @@
   // TODO(sad): https://crbug.com/645602
 }
 
 bool GpuMain::EnsureSandboxInitialized(
     gpu::GpuWatchdogThread* watchdog_thread) {
   // TODO(sad): https://crbug.com/645602
   return true;
 }
 
 }  // namespace ui