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

ui/ozone/platform/drm/BUILD.gn

 # 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.
 
 import("//build/config/linux/pkg_config.gni")
 import("//ui/ozone/ozone.gni")
 
 declare_args() {
   use_mesa_platform_null = false
   use_drm_atomic = false
+  ozone_use_vgem_map = false
 }
 
 pkg_config("libdrm") {
   packages = [ "libdrm" ]
 }
 
 source_set("drm_common") {
   sources = [
     "common/client_native_pixmap_factory_drm.cc",
     "common/client_native_pixmap_factory_drm.h",
@@ skipping 137 matching lines @@
 
 if (ozone_platform_gbm) {
   pkg_config("libgbm") {
     packages = [ "gbm" ]
   }
 
   source_set("gbm") {
     sources = [
       "common/client_native_pixmap_factory_gbm.cc",
       "common/client_native_pixmap_factory_gbm.h",
+      "gpu/client_native_pixmap_vgem.cc",
+      "gpu/client_native_pixmap_vgem.h",
       "gpu/gbm_buffer.cc",
       "gpu/gbm_buffer.h",
       "gpu/gbm_buffer_base.cc",
       "gpu/gbm_buffer_base.h",
       "gpu/gbm_device.cc",
       "gpu/gbm_device.h",
       "gpu/gbm_surface.cc",
       "gpu/gbm_surface.h",
       "gpu/gbm_surface_factory.cc",
       "gpu/gbm_surface_factory.h",
@@ skipping 12 matching lines @@
     ]
 
     public_configs = [
       ":libgbm",
       "//third_party/khronos:khronos_headers",
     ]
 
     if (use_mesa_platform_null) {
       defines += [ "USE_MESA_PLATFORM_NULL" ]
     }
+
+    if (ozone_use_vgem_map) {
+      defines += [ "OZONE_USE_VGEM_MAP" ]

[reveman, 2015/08/06 12:08:35]

why is this define needed?

[dshwang, 2015/08/06 13:59:17]

upstream linux doesn't have vgem_drm.h, so only cros linux can use vgem_drm.h
with the define.

+    }
   }
 }