Fix blits from multisampled renderbuffers to alpha:false WebGL back buffer.

ui/gl/gl_image.cc

 // Copyright 2016 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 "ui/gl/gl_image.h"
 
 namespace gl {
 
+bool GLImage::BindTexImageWithInternalformat(unsigned target,
+                                             unsigned internalformat) {
+  return false;
+}
+
 bool GLImage::EmulatingRGB() const {
   return false;
 }
 
 GLImage::Type GLImage::GetType() const {
   return Type::NONE;
 }
 
 }  // namespace gl