Add swapBuffer call to SkGLContextHelper.

R=bsalomon@google.com

Review URL: https://codereview.chromium.org/26701002

git-svn-id: http://skia.googlecode.com/svn/trunk@11682 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/gpu/gl/SkMesaGLContext.h b/include/gpu/gl/SkMesaGLContext.h
index 6470d2e..55235fa 100644
--- a/include/gpu/gl/SkMesaGLContext.h
+++ b/include/gpu/gl/SkMesaGLContext.h
@@ -22,6 +22,7 @@
     virtual ~SkMesaGLContext();
 
     virtual void makeCurrent() const SK_OVERRIDE;
+    virtual void swapBuffers() const SK_OVERRIDE;
 
     class AutoContextRestore {
     public: