Remove deprecated Ozone initialization functions.

ui/ozone/platform/x11/ozone_platform_x11.cc

Index: ui/ozone/platform/x11/ozone_platform_x11.cc
diff --git a/ui/ozone/platform/x11/ozone_platform_x11.cc b/ui/ozone/platform/x11/ozone_platform_x11.cc
index 9f515aca5da86dce3ec2a4d61e06b9a75d3d72a0..700d8225ad15df924ad7ad0b68d37aac1f154cc6 100644
--- a/ui/ozone/platform/x11/ozone_platform_x11.cc
+++ b/ui/ozone/platform/x11/ozone_platform_x11.cc
@@ -94,8 +94,6 @@ class OzonePlatformX11 : public OzonePlatform {
     gpu_platform_support_host_.reset(CreateStubGpuPlatformSupportHost());
   }
 
-  void InitializeUI() override { NOTREACHED(); }
-
   void InitializeGPU(const InitParams& params) override {
     InitializeCommon(params);
 
@@ -107,8 +105,6 @@ class OzonePlatformX11 : public OzonePlatform {
     surface_factory_ozone_ = base::MakeUnique<X11SurfaceFactory>();
   }
 
-  void InitializeGPU() override { NOTREACHED(); }
-
   base::MessageLoop::Type GetMessageLoopTypeForGpu() override {
     // When Ozone X11 backend is running use an UI loop to grab Expose events.
     // See GLSurfaceGLX and https://crbug.com/326995.