gpu: Allow waiting on sync tokens without sync token client.

services/ui/gpu/gpu_service.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_service.h"
 
 #include "base/bind.h"
 #include "base/debug/crash_logging.h"
 #include "base/memory/shared_memory.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ skipping 65 matching lines @@
       media::GpuVideoDecodeAccelerator::GetCapabilities(gpu_preferences_);
   gpu_info_.video_encode_accelerator_supported_profiles =
       media::GpuVideoEncodeAccelerator::GetSupportedProfiles(gpu_preferences_);
   gpu_info_.jpeg_decode_accelerator_supported =
       media::GpuJpegDecodeAcceleratorFactoryProvider::
           IsAcceleratedJpegDecodeSupported();
   gpu_host_->DidInitialize(gpu_info_);
 
   sync_point_manager_ = sync_point_manager;
   if (!sync_point_manager_) {
-    const bool allow_threaded_wait = false;
-    owned_sync_point_manager_ =
-        base::MakeUnique<gpu::SyncPointManager>(allow_threaded_wait);
+    owned_sync_point_manager_ = base::MakeUnique<gpu::SyncPointManager>();
     sync_point_manager_ = owned_sync_point_manager_.get();
   }
 
   // Defer creation of the render thread. This is to prevent it from handling
   // IPC messages before the sandbox has been enabled and all other necessary
   // initialization has succeeded.
   gpu_channel_manager_.reset(new gpu::GpuChannelManager(
       gpu_preferences_, this, watchdog_thread_.get(),
       base::ThreadTaskRunnerHandle::Get().get(), io_runner_.get(),
       shutdown_event ? shutdown_event : &shutdown_event_, sync_point_manager_,
@@ skipping 84 matching lines @@
   mojo::ScopedMessagePipeHandle channel_handle;
   IPC::ChannelHandle handle = gpu_channel_manager_->EstablishChannel(
       client_id, client_tracing_id, preempts, allow_view_command_buffers,
       allow_real_time_streams);
   channel_handle.reset(handle.mojo_handle);
   media_gpu_channel_manager_->AddChannel(client_id);
   callback.Run(std::move(channel_handle));
 }
 
 }  // namespace ui