ozone: Add post message loop initialization hook

ui/ozone/platform/drm/ozone_platform_gbm.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 "ui/ozone/platform/drm/ozone_platform_gbm.h"
 
 #include <dlfcn.h>
 #include <gbm.h>
 #include <stdlib.h>
 
@@ skipping 176 matching lines @@
     // This makes sure that simple targets that do not handle display
     // configuration can still use the primary display.
     ForceInitializationOfPrimaryDisplay(gbm_, screen_manager_.get());
 
     window_delegate_manager_.reset(new DrmWindowManager());
     if (!surface_factory_ozone_)
       surface_factory_ozone_.reset(new GbmSurfaceFactory(use_surfaceless_));
 
     surface_factory_ozone_->InitializeGpu(drm_device_manager_.get(),
                                           window_delegate_manager_.get());
+  }
+
+  void InitializeGPUPostMainLoop() override {
     scoped_ptr<DrmGpuDisplayManager> ndd(new DrmGpuDisplayManager(
         screen_manager_.get(), gbm_,
         scoped_ptr<DrmDeviceGenerator>(new GbmDeviceGenerator())));
     gpu_platform_support_.reset(new DrmGpuPlatformSupport(
         drm_device_manager_.get(), window_delegate_manager_.get(),
         screen_manager_.get(), ndd.Pass()));
   }
 
  private:
   // Objects in both processes.
@@ skipping 32 matching lines @@
 OzonePlatform* CreateOzonePlatformGbm() {
   base::CommandLine* cmd = base::CommandLine::ForCurrentProcess();
 #if defined(USE_MESA_PLATFORM_NULL)
   // Only works with surfaceless.
   cmd->AppendSwitch(switches::kOzoneUseSurfaceless);
 #endif
   return new OzonePlatformGbm(cmd->HasSwitch(switches::kOzoneUseSurfaceless));
 }
 
 }  // namespace ui