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

content/content_common.gypi

Index: content/content_common.gypi
diff --git a/content/content_common.gypi b/content/content_common.gypi
index 97590dfc1079b75503e43e788c246327bd771722..371f0a52fa1a35810971bd60ebab47d465b60a6a 100644
--- a/content/content_common.gypi
+++ b/content/content_common.gypi
@@ -36,6 +36,7 @@
   'variables': {
     'use_v4lplugin%': 0,
     'use_v4l2_codec%': 0,
+    'use_vgem_map%': 0,
     'public_common_sources': [
       'public/common/appcache_info.h',
       'public/common/bindings_policy.h',
@@ -1094,5 +1095,8 @@
         'common/gpu/gpu_memory_buffer_factory_ozone_native_pixmap.h',
       ],
     }],
+    ['use_vgem_map==1', {
+      'defines': ['USE_VGEM_MAP'],
+    }],
   ],
 }