services/ui: Allow injecting the IO thread task runner for gpu channel.

services/ui/public/cpp/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/public/cpp/gpu_service.h"
 
 #include "base/command_line.h"
 #include "base/memory/singleton.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
@@ skipping 17 matching lines @@
                    base::Bind(callback, std::move(established_channel_host)));
 }
 
 }  // namespace
 
 GpuService::GpuService(shell::Connector* connector)
     : main_task_runner_(base::ThreadTaskRunnerHandle::Get()),
       connector_(connector),
       shutdown_event_(base::WaitableEvent::ResetPolicy::AUTOMATIC,
                       base::WaitableEvent::InitialState::NOT_SIGNALED),
-      io_thread_("GPUIOThread"),
       gpu_memory_buffer_manager_(new MojoGpuMemoryBufferManager),
       is_establishing_(false),
       establishing_condition_(&lock_) {
   DCHECK(main_task_runner_);
   DCHECK(connector_);
-  base::Thread::Options thread_options(base::MessageLoop::TYPE_IO, 0);
-  thread_options.priority = base::ThreadPriority::NORMAL;
-  CHECK(io_thread_.StartWithOptions(thread_options));
 }
 
 GpuService::~GpuService() {
   DCHECK(IsMainThread());
   if (gpu_channel_)
     gpu_channel_->DestroyChannel();
 }
 
 // static
 std::unique_ptr<GpuService> GpuService::Initialize(
     shell::Connector* connector) {
   return base::WrapUnique(new GpuService(connector));
 }
 
+void GpuService::SetIOThreadTaskRunner(
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
+  DCHECK(!io_task_runner_);
+  io_task_runner_ = std::move(task_runner);
+}
+
 void GpuService::EstablishGpuChannel(
     const gpu::GpuChannelEstablishedCallback& callback) {
   base::AutoLock auto_lock(lock_);
   auto runner = base::ThreadTaskRunnerHandle::Get();
   scoped_refptr<gpu::GpuChannelHost> channel = GetGpuChannelLocked();
   if (channel) {
     PostTask(runner, FROM_HERE, callback, std::move(channel));
     return;
   }
   establish_callbacks_.push_back(
@@ skipping 127 matching lines @@
     i.Run(gpu_channel_);
   establish_callbacks_.clear();
 }
 
 bool GpuService::IsMainThread() {
   return main_task_runner_->BelongsToCurrentThread();
 }
 
 scoped_refptr<base::SingleThreadTaskRunner>
 GpuService::GetIOThreadTaskRunner() {
-  return io_thread_.task_runner();
+  if (!io_task_runner_) {
+    io_thread_.reset(new base::Thread("GPUIOThread"));
+    base::Thread::Options thread_options(base::MessageLoop::TYPE_IO, 0);
+    thread_options.priority = base::ThreadPriority::NORMAL;
+    CHECK(io_thread_->StartWithOptions(thread_options));
+    io_task_runner_ = io_thread_->task_runner();
+  }
+  return io_task_runner_;
 }
 
 std::unique_ptr<base::SharedMemory> GpuService::AllocateSharedMemory(
     size_t size) {
   mojo::ScopedSharedBufferHandle handle =
       mojo::SharedBufferHandle::Create(size);
   if (!handle.is_valid())
     return nullptr;
 
   base::SharedMemoryHandle platform_handle;
   size_t shared_memory_size;
   bool readonly;
   MojoResult result = mojo::UnwrapSharedMemoryHandle(
       std::move(handle), &platform_handle, &shared_memory_size, &readonly);
   if (result != MOJO_RESULT_OK)
     return nullptr;
   DCHECK_EQ(shared_memory_size, size);
 
   return base::MakeUnique<base::SharedMemory>(platform_handle, readonly);
 }
 
 }  // namespace ui