mus::GpuService: Support establish GpuChannel asynchronously.

components/mus/common/gpu_service.h

Index: components/mus/common/gpu_service.h
diff --git a/components/mus/common/gpu_service.h b/components/mus/common/gpu_service.h
index 91be13f3d90cce73086c0f801cda3c15834b56be..d50c03fdbe9e84fa86bde17e3cee20dc600744a3 100644
--- a/components/mus/common/gpu_service.h
+++ b/components/mus/common/gpu_service.h
@@ -12,7 +12,9 @@
 #include "base/synchronization/lock.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/thread.h"
+#include "components/mus/common/mojo_gpu_memory_buffer_manager.h"
 #include "components/mus/common/mus_common_export.h"
+#include "components/mus/public/interfaces/gpu_service.mojom.h"
 #include "gpu/ipc/client/gpu_channel_host.h"
 
 namespace shell {
@@ -21,22 +23,36 @@ class Connector;
 
 namespace mus {
 
-class MojoGpuMemoryBufferManager;
-
 class MUS_COMMON_EXPORT GpuService : public gpu::GpuChannelHostFactory {
  public:
-  scoped_refptr<gpu::GpuChannelHost> EstablishGpuChannel(
-      shell::Connector* connector);
+  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();
+  }
 
   static bool UseChromeGpuCommandBuffer();
+
+  // The GpuService has to be initialized in the main thread before establishing
+  // the gpu channel.
+  static void Initialize(shell::Connector* connector);
   static GpuService* GetInstance();
 
  private:
   friend struct base::DefaultSingletonTraits<GpuService>;
 
-  GpuService();
+  explicit GpuService(shell::Connector* connector);
   ~GpuService() override;
 
+  scoped_refptr<gpu::GpuChannelHost> GetGpuChannelLocked();
+  void EstablishGpuChannelOnMainThread();
+  void EstablishGpuChannelOnMainThreadLocked();
+  void EstablishGpuChannelOnMainThreadDone(
+      int client_id,
+      mojom::ChannelHandlePtr channel_handle,
+      mojom::GpuInfoPtr gpu_info);
+
   // gpu::GpuChannelHostFactory overrides:
   bool IsMainThread() override;
   scoped_refptr<base::SingleThreadTaskRunner> GetIOThreadTaskRunner() override;
@@ -44,13 +60,18 @@ class MUS_COMMON_EXPORT GpuService : public gpu::GpuChannelHostFactory {
       size_t size) override;
 
   base::MessageLoop* main_message_loop_;
+  shell::Connector* connector_;
   base::WaitableEvent shutdown_event_;
   base::Thread io_thread_;
   std::unique_ptr<MojoGpuMemoryBufferManager> gpu_memory_buffer_manager_;
 
-  // Lock for |gpu_channel_|.
+  // Lock for |gpu_channel_|, |establish_callbacks_| & |is_establishing_|.
   base::Lock lock_;
+  bool is_establishing_;
+  mus::mojom::GpuServicePtr gpu_service_;
   scoped_refptr<gpu::GpuChannelHost> gpu_channel_;
+  std::vector<base::Closure> establish_callbacks_;
+  base::ConditionVariable establishing_condition_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuService);
 };