Add a second unsafe ES3 API in command buffer.

gpu/command_buffer/client/gles2_implementation_impl_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 191 matching lines @@
 }
 
 void GLES2Implementation::CompileShader(GLuint shader) {
   GPU_CLIENT_SINGLE_THREAD_CHECK();
   GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glCompileShader(" << shader
                      << ")");
   helper_->CompileShader(shader);
   CheckGLError();
 }
 
+void GLES2Implementation::CopyBufferSubData(GLenum readtarget,
+                                            GLenum writetarget,
+                                            GLintptr readoffset,
+                                            GLintptr writeoffset,
+                                            GLsizeiptr size) {
+  GPU_CLIENT_SINGLE_THREAD_CHECK();
+  GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glCopyBufferSubData("
+                     << GLES2Util::GetStringBufferTarget(readtarget) << ", "
+                     << GLES2Util::GetStringBufferTarget(writetarget) << ", "
+                     << readoffset << ", " << writeoffset << ", " << size
+                     << ")");
+  if (readoffset < 0) {
+    SetGLError(GL_INVALID_VALUE, "glCopyBufferSubData", "readoffset < 0");
+    return;
+  }
+  if (writeoffset < 0) {
+    SetGLError(GL_INVALID_VALUE, "glCopyBufferSubData", "writeoffset < 0");
+    return;
+  }
+  if (size < 0) {
+    SetGLError(GL_INVALID_VALUE, "glCopyBufferSubData", "size < 0");
+    return;
+  }
+  helper_->CopyBufferSubData(readtarget, writetarget, readoffset, writeoffset,
+                             size);
+  CheckGLError();
+}
+
 void GLES2Implementation::CopyTexImage2D(GLenum target,
                                          GLint level,
                                          GLenum internalformat,
                                          GLint x,
                                          GLint y,
                                          GLsizei width,
                                          GLsizei height,
                                          GLint border) {
   GPU_CLIENT_SINGLE_THREAD_CHECK();
   GPU_CLIENT_LOG(
@@ skipping 2057 matching lines @@
 
 void GLES2Implementation::BlendBarrierKHR() {
   GPU_CLIENT_SINGLE_THREAD_CHECK();
   GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glBlendBarrierKHR("
                      << ")");
   helper_->BlendBarrierKHR();
   CheckGLError();
 }
 
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GLES2_IMPLEMENTATION_IMPL_AUTOGEN_H_