[Ozone] Update GYP and GN to include a DRM platform

ui/ozone/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("//ui/ozone/ozone.gni")
 import("//testing/test.gni")
 
 # The list of platforms that will be built.
 ozone_platforms = []
 
@@ skipping 11 matching lines @@
 if (ozone_platform_test) {
   ozone_platforms += [ "test" ]
   ozone_platform_deps += [ "platform/test" ]
 }
 
 if (ozone_platform_caca) {
   ozone_platforms += [ "caca" ]
   ozone_platform_deps += [ "platform/caca" ]
 }
 
-if (ozone_platform_dri) {
-  ozone_platforms += [ "dri" ]
+if (ozone_platform_dri || ozone_platform_drm) {

[brettw, 2015/03/13 23:14:48]

Can you explain here why dri and drm imply each other? Why do we have separate
flags for these in the first place?

+  ozone_platforms += [
+    "dri",
+    "drm",
+  ]
   ozone_platform_deps += [ "platform/drm" ]
   ozone_platform_test_deps += [ "platform/drm:drm_unittests" ]
 }
 
 if (ozone_platform_gbm) {
   ozone_platforms += [ "gbm" ]
   ozone_platform_deps += [ "platform/drm:gbm" ]
 }
 
 platform_list_cc_file = "$target_gen_dir/platform_list.cc"
@@ skipping 131 matching lines @@
     "common/display_util_unittest.cc",
     "run_all_unittests.cc",
   ]
 
   deps = [
            "//base/test:test_support",
            "//testing/gtest",
            "//ui/gfx/geometry",
          ] + ozone_platform_test_deps
 }