Allow creating GLImage-backed textures with glTexStorage2D.

gpu/command_buffer/build_gles2_cmd_buffer.py

 #!/usr/bin/env python
 # 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.
 
 """code generator for GLES2 command buffers."""
 
 import itertools
 import os
 import os.path
@@ skipping 1034 matching lines @@
     ],
     'valid_es3': [
       'GL_TEXTURE_3D',
       'GL_TEXTURE_2D_ARRAY',
     ],
     'invalid': [
       'GL_TEXTURE_1D',
       'GL_TEXTURE_3D',
     ],
   },
+  'TextureBufferUsage': {
+    'type': 'GLenum',
+    'is_complete': True,
+    'valid': [
+      'GL_NONE',
+      'GL_TEXTURE_BUFFER_SCANOUT_CHROMIUM',
+    ],
+  },
   'TransformFeedbackBindTarget': {
     'type': 'GLenum',
     'valid': [
       'GL_TRANSFORM_FEEDBACK',
     ],
     'invalid': [
       'GL_TEXTURE_2D',
     ],
   },
   'TransformFeedbackPrimitiveMode': {
@@ skipping 402 matching lines @@
     ],
   },
 
   'TextureParameter': {
     'type': 'GLenum',
     'valid': [
       'GL_TEXTURE_MAG_FILTER',
       'GL_TEXTURE_MIN_FILTER',
       'GL_TEXTURE_WRAP_S',
       'GL_TEXTURE_WRAP_T',
+      'GL_TEXTURE_BUFFER_USAGE_CHROMIUM',

[Zhenyao Mo, 2017/06/20 00:14:30]

I am not sure this is the right thing to do. I think you need to add this
dynamically in FeatureInfo::Initialize() when you add the related extension.

For example, if it's WebGL contexts, since we removed many validation codes in
blink side, you don't want to leak this to WebGL.

     ],
     'valid_es3': [
       'GL_TEXTURE_BASE_LEVEL',
       'GL_TEXTURE_COMPARE_FUNC',
       'GL_TEXTURE_COMPARE_MODE',
       'GL_TEXTURE_IMMUTABLE_FORMAT',
       'GL_TEXTURE_IMMUTABLE_LEVELS',
       'GL_TEXTURE_MAX_LEVEL',
       'GL_TEXTURE_MAX_LOD',
       'GL_TEXTURE_MIN_LOD',
@@ skipping 9818 matching lines @@
   Format(gen.generated_cpp_filenames)
 
   if gen.errors > 0:
     print "%d errors" % gen.errors
     return 1
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))