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

ui/ozone/ozone.gni

Index: ui/ozone/ozone.gni
diff --git a/ui/ozone/ozone.gni b/ui/ozone/ozone.gni
index e307a352d578184fc4ba74e32c3a469e118c9d61..e64ad5186c368dbc77340d136646f0786c21852d 100644
--- a/ui/ozone/ozone.gni
+++ b/ui/ozone/ozone.gni
@@ -5,6 +5,10 @@
 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() {