Add GN build for parts of gpu and ozone.

ui/gfx/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/ui.gni")
 
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
 }
+if (use_ozone) {
+  import("//ui/ozone/ozone.gni")
+}
 
 # Several targets want to include this header file, and some of them are
 # child dependencies of "gfx". Therefore, we separate it out here so multiple
 # targets can all have a dependency for header checking purposes without
 # creating circular dependencies.
 source_set("gfx_export") {
   sources = [
     "gfx_export.h",
   ]
 }
@@ skipping 308 matching lines @@
     sources -= [
       "ozone/impl/file_surface_factory.cc",
       "ozone/impl/file_surface_factory.h",
       "ozone/surface_factory_ozone.cc",
       "ozone/surface_factory_ozone.h",
       "ozone/surface_ozone.h",
       "ozone/overlay_candidates_ozone.cc",
       "ozone/overlay_candidates_ozone.h",
     ]
   }
-  if (ozone_platform_dri) {
+  if (use_ozone && ozone_platform_dri) {
     configs += [ "//build/config/linux:dridrm" ]
   } else {
     sources -= [
       "ozone/dri/dri_skbitmap.cc",
       "ozone/dri/dri_skbitmap.h",
       "ozone/dri/dri_surface.cc",
       "ozone/dri/dri_surface.h",
       "ozone/dri/dri_surface_factory.cc",
       "ozone/dri/dri_surface_factory.h",
       "ozone/dri/dri_vsync_provider.cc",
@@ skipping 170 matching lines @@
     ]
 
     configs += [ "//build/config/linux:x11" ]
 
     deps = [
       ":gfx_export",
       "//base"
     ]
   }
 }