ozone: scenic: Remove stub GpuPlatformSupportHost

This was replaced by ScenicGpuHost but not removed.

Bug: 861853
Test: compile
Change-Id: I6c982b87a6f9d64abb975ebfd4ac2d024333d503
Reviewed-on: https://chromium-review.googlesource.com/c/1354480Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Commit-Queue: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611942}

ui/ozone/platform/scenic/ozone_platform_scenic.cc

@@ -121,7 +121,6 @@ class OzonePlatformScenic
     overlay_manager_ = std::make_unique<StubOverlayManager>();
     input_controller_ = CreateStubInputController();
     cursor_factory_ozone_ = std::make_unique<BitmapCursorFactoryOzone>();
-    gpu_platform_support_host_.reset(CreateStubGpuPlatformSupportHost());
 
     base::MessageLoopCurrent::Get()->AddDestructionObserver(this);
 
@@ -161,7 +160,6 @@ class OzonePlatformScenic
   std::unique_ptr<PlatformEventSource> platform_event_source_;
   std::unique_ptr<CursorFactoryOzone> cursor_factory_ozone_;
   std::unique_ptr<InputController> input_controller_;
-  std::unique_ptr<GpuPlatformSupportHost> gpu_platform_support_host_;
   std::unique_ptr<OverlayManagerOzone> overlay_manager_;
   std::unique_ptr<ScenicGpuHost> scenic_gpu_host_;
   std::unique_ptr<ScenicGpuService> scenic_gpu_service_;