gpu: Add async pixel transfer interface, stub and tests.

ui/gl/gl.gyp

 # Copyright (c) 2012 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': {
     'chromium_code': 1,
   },
 
   'targets': [
@@ skipping 22 matching lines @@
       ],
       'direct_dependent_settings': {
         'include_dirs': [
           '<(gl_binding_output_dir)',
         ],
       },
       'export_dependent_settings': [
         '<(DEPTH)/third_party/mesa/mesa.gyp:mesa_headers',
       ],
      'sources': [
+        'async_pixel_transfer_delegate.h',
         'gl_bindings.h',
         'gl_bindings_skia_in_process.cc',
         'gl_bindings_skia_in_process.h',
         'gl_context.cc',
         'gl_context.h',
         'gl_context_android.cc',
         'gl_context_linux.cc',
         'gl_context_mac.mm',
         'gl_context_osmesa.cc',
         'gl_context_osmesa.h',
@@ skipping 171 matching lines @@
             'gl_context_nsview.mm',
             'gl_context_nsview.h',
             'gl_surface_nsview.mm',
             'gl_surface_nsview.h',
           ],
         }],
         ['OS=="android"', {
           'sources': [
             'android_native_window.cc',
             'android_native_window.h',
+            'async_pixel_transfer_delegate_android.cc',
+            'async_pixel_transfer_delegate_android.h'
           ],
           'sources!': [
             'gl_context_osmesa.cc',
             'system_monitor_posix.cc',
           ],
           'defines': [
             'GL_GLEXT_PROTOTYPES',
             'EGL_EGLEXT_PROTOTYPES',
           ],
         }],
       ],
     },
   ],
 }