Add swapBuffer call to SkGLContextHelper.

src/gpu/gl/nacl/SkNativeGLContext_nacl.cpp

 
 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "gl/SkNativeGLContext.h"
 
 SkNativeGLContext::AutoContextRestore::AutoContextRestore() {
@@ skipping 14 matching lines @@
 
 void SkNativeGLContext::destroyGLContext() {
 }
 
 const GrGLInterface* SkNativeGLContext::createGLContext() {
     return NULL;
 }
 
 void SkNativeGLContext::makeCurrent() const {
 }
+
+void SkNativeGLContext::swapBuffers() const {
+}