ozone: Implement zero/one-copy texture for Ozone GBM.

ui/ozone/platform/drm/gbm.gypi

 # 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.
 
 {
   'variables': {
     'internal_ozone_platform_deps': [
       'ozone_platform_gbm',
     ],
     'internal_ozone_platforms': [
       'gbm',
     ],
     'use_mesa_platform_null%': 0,
+
+    # TODO(dshwang): remove this flag when all gbm hardware supports vgem map.
+    # crbug.com/519587
+    'use_vgem_map%': 0,
   },
   'targets': [
     {
       'target_name': 'ozone_platform_gbm',
       'type': 'static_library',
       'dependencies': [
         '../../base/base.gyp:base',
         '../../build/linux/system.gyp:libdrm',
         '../../build/linux/system.gyp:gbm',
         '../../skia/skia.gyp:skia',
@@ skipping 23 matching lines @@
         'gpu/gbm_surface_factory.h',
         'gpu/gbm_surfaceless.cc',
         'gpu/gbm_surfaceless.h',
         'ozone_platform_gbm.cc',
         'ozone_platform_gbm.h',
       ],
       'conditions': [
         ['use_mesa_platform_null==1', {
           'defines': ['USE_MESA_PLATFORM_NULL'],
         }],
+        ['use_vgem_map==1', {
+          'defines': ['USE_VGEM_MAP'],
+          'sources': [
+            'gpu/client_native_pixmap_vgem.cc',
+            'gpu/client_native_pixmap_vgem.h',
+          ],
+        }],
       ],
     },
   ],
 }