Add swapBuffer call to SkGLContextHelper.

src/gpu/gl/angle/SkANGLEGLContext.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/SkANGLEGLContext.h"
 
@@ skipping 87 matching lines @@
     }
 
     return interface;
 }
 
 void SkANGLEGLContext::makeCurrent() const {
     if (!eglMakeCurrent(fDisplay, fSurface, fSurface, fContext)) {
         SkDebugf("Could not set the context.\n");
     }
 }
+
+void SkANGLEGLContext::swapBuffers() const {
+    if (!eglSwapBuffers(fDisplay, fSurface)) {
+        SkDebugf("Could not complete eglSwapBuffers.\n");
+    }
+}