Implement client side PBOs for glReadPixel

gpu/gpu.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': {
     'nacl_win64_target': 0,
   },
   'includes': [
     'gpu_common.gypi',
@@ skipping 245 matching lines @@
         'command_buffer/tests/gl_shared_resources_unittests.cc',
         'command_buffer/tests/gl_tests_main.cc',
         'command_buffer/tests/gl_test_utils.cc',
         'command_buffer/tests/gl_test_utils.h',
         'command_buffer/tests/gl_texture_mailbox_unittests.cc',
         'command_buffer/tests/gl_texture_storage_unittests.cc',
         'command_buffer/tests/gl_unittests.cc',
         'command_buffer/tests/gl_virtual_contexts_unittests.cc',
         'command_buffer/tests/gl_stream_draw_unittests.cc',
         'command_buffer/tests/occlusion_query_unittests.cc',
+        'command_buffer/tests/gl_readback_unittests.cc',
       ],
       'conditions': [
         ['OS == "android" and gtest_target_type == "shared_library"', {
           'dependencies': [
             '../testing/android/native_test.gyp:native_test_native_code',
           ],
         }],
       ],
       # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
       'msvs_disabled_warnings': [ 4267, ],
@@ skipping 225 matching lines @@
             'input_shlib_path': '<(SHARED_LIB_DIR)/<(SHARED_LIB_PREFIX)gl_tests<(SHARED_LIB_SUFFIX)',
           },
           'includes': [
             '../build/apk_test.gypi',
           ],
         },
       ],
     }],
   ],
 }