Revert of services/ui: Have an explicit lifetime/ownership of ui::GpuService.

services/ui/common/gpu_service.h

 // 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.
 
 #ifndef SERVICES_UI_COMMON_GPU_SERVICE_H_
 #define SERVICES_UI_COMMON_GPU_SERVICE_H_
 
 #include <stdint.h>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/single_thread_task_runner.h"
 #include "base/synchronization/lock.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/thread.h"
 #include "gpu/ipc/client/gpu_channel_host.h"
 #include "services/ui/common/mojo_gpu_memory_buffer_manager.h"
 #include "services/ui/common/mus_common_export.h"
 #include "services/ui/public/interfaces/gpu_service.mojom.h"
 
 namespace shell {
 class Connector;
 }
 
 namespace ui {
 
 class MUS_COMMON_EXPORT GpuService : public gpu::GpuChannelHostFactory {
  public:
-  ~GpuService() override;
-
   void EstablishGpuChannel(const base::Closure& callback);
   scoped_refptr<gpu::GpuChannelHost> EstablishGpuChannelSync();
   scoped_refptr<gpu::GpuChannelHost> GetGpuChannel();
   gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager() const {
     return gpu_memory_buffer_manager_.get();
   }
 
   // The GpuService has to be initialized in the main thread before establishing
   // the gpu channel.
-  static std::unique_ptr<GpuService> Initialize(shell::Connector* connector);
+  static void Initialize(shell::Connector* connector);
+  // The GpuService has to be terminated in the main thread.
+  static void Terminate();
   static GpuService* GetInstance();
 
  private:
   friend struct base::DefaultSingletonTraits<GpuService>;
 
   explicit GpuService(shell::Connector* connector);
+  ~GpuService() override;
 
   scoped_refptr<gpu::GpuChannelHost> GetGpuChannelLocked();
   void EstablishGpuChannelOnMainThread();
   void EstablishGpuChannelOnMainThreadSyncLocked();
   void EstablishGpuChannelOnMainThreadDone(
       bool locked,
       int client_id,
       mojom::ChannelHandlePtr channel_handle,
       mojom::GpuInfoPtr gpu_info);
 
@@ skipping 16 matching lines @@
   scoped_refptr<gpu::GpuChannelHost> gpu_channel_;
   std::vector<base::Closure> establish_callbacks_;
   base::ConditionVariable establishing_condition_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuService);
 };
 
 }  // namespace ui
 
 #endif  // COMPONENTS_MUS_PUBLIC_CPP_LIB_GPU_SERVICE_CONNECTION_H_