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
+
+  # TODO(dshwang): remove this flag when all gbm hardware supports vgem map.
+  # crbug.com/519587
+  use_vgem_map = false

[brettw, 2015/08/24 21:53:38]

Can you call this ozone_use_vgem_map instead? Does this ozone name make sense in
the way that you use it? I'd like to give hints about what flags affect in their
name. If this is easy (i.e. bots don't depend on the old name now) then it would
be nice to rename even if we keep it in the BUILD.gn file according to my other
comment.

[spang, 2015/08/24 22:09:09]

The scope is narrower than ozone, it applies to Chrome OS kernel in particular.

If we want some more descriptive words, maybe add "linux kernel" or "chromeos
kernel" ?

[dshwang, 2015/08/26 12:02:43]

got it. I'll rename it to CHROMEOS_USE_VGEM_MAP with comments
# 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.

[dshwang, 2015/08/26 14:18:02]

I didn't rename it. done to update comments.

 }
 
 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
   }
 }