Add a second unsafe ES3 API in command buffer.

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 225 matching lines @@
                              uint32_t data_shm_id,
                              uint32_t data_shm_offset) {
   gles2::cmds::CompressedTexSubImage2D* c =
       GetCmdSpace<gles2::cmds::CompressedTexSubImage2D>();
   if (c) {
     c->Init(target, level, xoffset, yoffset, width, height, format, imageSize,
             data_shm_id, data_shm_offset);
   }
 }
 
+void CopyBufferSubData(GLenum readtarget,
+                       GLenum writetarget,
+                       GLintptr readoffset,
+                       GLintptr writeoffset,
+                       GLsizeiptr size) {
+  gles2::cmds::CopyBufferSubData* c =
+      GetCmdSpace<gles2::cmds::CopyBufferSubData>();
+  if (c) {
+    c->Init(readtarget, writetarget, readoffset, writeoffset, size);
+  }
+}
+
 void CopyTexImage2D(GLenum target,
                     GLint level,
                     GLenum internalformat,
                     GLint x,
                     GLint y,
                     GLsizei width,
                     GLsizei height) {
   gles2::cmds::CopyTexImage2D* c = GetCmdSpace<gles2::cmds::CopyTexImage2D>();
   if (c) {
     c->Init(target, level, internalformat, x, y, width, height);
@@ skipping 1664 matching lines @@
 }
 
 void BlendBarrierKHR() {
   gles2::cmds::BlendBarrierKHR* c = GetCmdSpace<gles2::cmds::BlendBarrierKHR>();
   if (c) {
     c->Init();
   }
 }
 
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GLES2_CMD_HELPER_AUTOGEN_H_