Add GL_CHROMIUM_screen_space_antialiasing to support alternative AA

gpu/command_buffer/client/gles2_cmd_helper_autogen.h

 // 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.
 
 // This file is auto-generated from
 // gpu/command_buffer/build_gles2_cmd_buffer.py
 // It's formatted by clang-format using chromium coding style:
 //    clang-format -i -style=chromium filename
 // DO NOT EDIT!
 
@@ skipping 2996 matching lines @@
   }
 }
 
 void BlendBarrierKHR() {
   gles2::cmds::BlendBarrierKHR* c = GetCmdSpace<gles2::cmds::BlendBarrierKHR>();
   if (c) {
     c->Init();
   }
 }
 
+void ApplyScreenSpaceAntialiasing() {
+  gles2::cmds::ApplyScreenSpaceAntialiasing* c =
+      GetCmdSpace<gles2::cmds::ApplyScreenSpaceAntialiasing>();
+  if (c) {
+    c->Init();
+  }
+}
+
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GLES2_CMD_HELPER_AUTOGEN_H_