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 6a1ef2277a15d75217d7dac6ca06eb4e43e91bf5..4eaeaaf5f12118d1850b4daa2c25554cef86b191 100644
--- a/ui/ozone/public/gpu_platform_support_host.h
+++ b/ui/ozone/public/gpu_platform_support_host.h
@@ -34,13 +34,11 @@ class OZONE_BASE_EXPORT GpuPlatformSupportHost : public IPC::Listener {
       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.
   virtual void OnChannelDestroyed(int host_id) = 0;
+
+  virtual void BindToCurrentThread() = 0;
 };
 
 // create a stub implementation.