Revert of gpu: Completely remove GpuProcessHostUIShim.

ui/ozone/platform/drm/host/drm_gpu_platform_support_host.h

Index: ui/ozone/platform/drm/host/drm_gpu_platform_support_host.h
diff --git a/ui/ozone/platform/drm/host/drm_gpu_platform_support_host.h b/ui/ozone/platform/drm/host/drm_gpu_platform_support_host.h
index 37f7e4551ff25e7af1d60f6279565bafd12b31ac..f446d32bafcd12718cc5a06cdd37dc21f752abcb 100644
--- a/ui/ozone/platform/drm/host/drm_gpu_platform_support_host.h
+++ b/ui/ozone/platform/drm/host/drm_gpu_platform_support_host.h
@@ -30,15 +30,15 @@
                                   public GpuThreadAdapter,
                                   public IPC::Sender {
  public:
-  explicit DrmGpuPlatformSupportHost(DrmCursor* cursor);
+  DrmGpuPlatformSupportHost(DrmCursor* cursor);
   ~DrmGpuPlatformSupportHost() override;
 
   // GpuPlatformSupportHost:
   void OnGpuProcessLaunched(
       int host_id,
-      scoped_refptr<base::SingleThreadTaskRunner> ui_runner,
       scoped_refptr<base::SingleThreadTaskRunner> send_runner,
       const base::Callback<void(IPC::Message*)>& send_callback) override;
+  void OnChannelEstablished() override;
   void OnChannelDestroyed(int host_id) override;
 
   // IPC::Listener:
@@ -95,7 +95,6 @@
                               const gfx::Rect& bounds) override;
 
  private:
-  void OnChannelEstablished();
   bool OnMessageReceivedForDrmDisplayHostManager(const IPC::Message& message);
   void OnUpdateNativeDisplays(
       const std::vector<DisplaySnapshot_Params>& displays);
@@ -114,7 +113,6 @@
   int host_id_ = -1;
   bool channel_established_ = false;
 
-  scoped_refptr<base::SingleThreadTaskRunner> ui_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> send_runner_;
   base::Callback<void(IPC::Message*)> send_callback_;
 
@@ -123,9 +121,6 @@
 
   DrmCursor* cursor_;                              // Not owned.
   base::ObserverList<GpuThreadObserver> gpu_thread_observers_;
-
-  base::WeakPtrFactory<DrmGpuPlatformSupportHost> weak_ptr_factory_;
-  DISALLOW_COPY_AND_ASSIGN(DrmGpuPlatformSupportHost);
 };
 
 }  // namespace ui