ozone gbm: whitelist 3 DRM ioctl code for native GpuMemoryBuffer.

ui/ozone/ozone.gni

 # 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.
 
 declare_args() {
   # Select platforms automatically. Turn this off for manual control.
   ozone_auto_platforms = true
+
+  # This enables memory-mapped access to accelerated graphics buffers via the
+  # VGEM ("virtual GEM") driver. This is currently only available on Chrome OS
+  # kernels and affects code in the GBM ozone platform.
+  # TODO(dshwang): remove this flag when all gbm hardware supports vgem map.
+  # crbug.com/519587
+  use_vgem_map = false

[brettw, 2015/08/28 19:21:43]

You can move this back to the old place now.

[dshwang, 2015/08/31 09:10:14]

If I move this to ui/ozone/platform/drm/BUILD.gn (i.e. old place), I encounter
following error.
ERROR at //ui/ozone/BUILD.gn:49:7: Undefined identifier
  if (use_vgem_map) {
      ^-----------

 }
 
 declare_args() {
   # The platform that will be active by default.
   ozone_platform = ""
 
   # Enable individual platforms.
   ozone_platform_caca = false
   ozone_platform_drm = false
   ozone_platform_egltest = false
   ozone_platform_gbm = false
   ozone_platform_ozonex = false
   ozone_platform_test = false
 
   if (ozone_auto_platforms) {
     # Use test as the default platform.
     ozone_platform = "test"
 
     # Build all platforms whose deps are in install-build-deps.sh.
     # Only these platforms will be compile tested by buildbots.
     ozone_platform_drm = true
     ozone_platform_test = true
     ozone_platform_egltest = true
   }
 }