gpu: Introduce GpuChannelEstablishFactory.

gpu/ipc/client/gpu_channel_host.h

Index: gpu/ipc/client/gpu_channel_host.h
diff --git a/gpu/ipc/client/gpu_channel_host.h b/gpu/ipc/client/gpu_channel_host.h
index 94fb98d71d6670bdf74bb0ce880a112b878d56db..994f812b229aafeb051647b9b1e1780fd2163029 100644
--- a/gpu/ipc/client/gpu_channel_host.h
+++ b/gpu/ipc/client/gpu_channel_host.h
@@ -43,6 +43,22 @@ class GpuMemoryBufferManager;
 
 namespace gpu {
 
+class GpuChannelHost;
+using GpuChannelEstablishedCallback =
+    base::Callback<void(scoped_refptr<GpuChannelHost>)>;
+
+class GPU_EXPORT GpuChannelEstablishFactory {
+ public:
+  virtual ~GpuChannelEstablishFactory() {}
+
+  virtual void EstablishGpuChannel(
+      const GpuChannelEstablishedCallback& callback) = 0;
+  virtual scoped_refptr<GpuChannelHost> EstablishGpuChannelSync() = 0;
+
+  static void SetInstance(GpuChannelEstablishFactory* instance);
+  static GpuChannelEstablishFactory* GetInstance();
+};
+
 class GPU_EXPORT GpuChannelHostFactory {
  public:
   virtual ~GpuChannelHostFactory() {}