Implement EXT_draw_buffers WebGL extention support in command buffer.

content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc

 // 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.
 
 #include "content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.h"
 
 #include "third_party/khronos/GLES2/gl2.h"
 #ifndef GL_GLEXT_PROTOTYPES
 #define GL_GLEXT_PROTOTYPES 1
 #endif
@@ skipping 1686 matching lines @@
   return gl_->AsyncTexSubImage2DCHROMIUM(
       target, level, xoffset, yoffset,
       width, height, format, type, pixels);
 }
 
 void WebGraphicsContext3DCommandBufferImpl::waitAsyncTexImage2DCHROMIUM(
     WGC3Denum target) {
   return gl_->WaitAsyncTexImage2DCHROMIUM(target);
 }
 
+void WebGraphicsContext3DCommandBufferImpl::drawBuffersEXT(
+    WGC3Dsizei n,
+    const WGC3Denum* bufs) {
+  gl_->DrawBuffersEXT(n, bufs);
+}
+
 GrGLInterface* WebGraphicsContext3DCommandBufferImpl::onCreateGrGLInterface() {
   return webkit::gpu::CreateCommandBufferSkiaGLBinding();
 }
 
 namespace {
 
 WGC3Denum convertReason(gpu::error::ContextLostReason reason) {
   switch (reason) {
   case gpu::error::kGuilty:
     return GL_GUILTY_CONTEXT_RESET_ARB;
@@ skipping 23 matching lines @@
 
 void WebGraphicsContext3DCommandBufferImpl::OnErrorMessage(
     const std::string& message, int id) {
   if (error_message_callback_) {
     WebKit::WebString str = WebKit::WebString::fromUTF8(message.c_str());
     error_message_callback_->onErrorMessage(str, id);
   }
 }
 
 }  // namespace content