Revert of gpu: Completely remove GpuProcessHostUIShim.

ui/ozone/public/gpu_platform_support_host.h

Index: ui/ozone/public/gpu_platform_support_host.h
diff --git a/ui/ozone/public/gpu_platform_support_host.h b/ui/ozone/public/gpu_platform_support_host.h
index 3fad96459b99b9d103e324aa70a26d3f21957ae9..6a1ef2277a15d75217d7dac6ca06eb4e43e91bf5 100644
--- a/ui/ozone/public/gpu_platform_support_host.h
+++ b/ui/ozone/public/gpu_platform_support_host.h
@@ -31,9 +31,12 @@
   // This is called from browser IO thread.
   virtual void OnGpuProcessLaunched(
       int host_id,
-      scoped_refptr<base::SingleThreadTaskRunner> ui_runner,
       scoped_refptr<base::SingleThreadTaskRunner> send_runner,
       const base::Callback<void(IPC::Message*)>& sender) = 0;
+
+  // Called when the channel is established.
+  // This is called from browser UI thread.
+  virtual void OnChannelEstablished() = 0;
 
   // Called when the GPU process is destroyed.
   // This is called from browser UI thread.