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,
+    'ozone_use_vgem_map%': 0,

[reveman, 2015/08/07 14:35:16]

just to be sure I understand. we have hardware that use gbm but doesn't support
vgem yet, correct? in that case, can you add a TODO about removing this flag
when all gbm hardware support vgem?

[vignatti (out of this project), 2015/08/07 14:51:25]

correct, but I don't think it's about hardware only or its driver supporting
dma-buf userspace mmap etc.

It's more about CrOS vs other Linux and their graphics subsystem allocator of
choice. For example, we were shipping out a Web view based on Ozone-GBM running
on Yocto, which doesn't have VGEM at all. So atm I think it's more about
choosing a graphics module, testing it, consolidate the implementation, decide
which is the one and so on.

[dshwang, 2015/08/07 15:36:46]

correct. Done.

   },
   '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'],
         }],
+        ['ozone_use_vgem_map==1', {
+          'defines': ['OZONE_USE_VGEM_MAP'],
+          'sources': [
+            'gpu/client_native_pixmap_vgem.cc',
+            'gpu/client_native_pixmap_vgem.h',
+          ],
+        }],
       ],
     },
   ],
 }