Cleanup: Mark some overridden methods with 'SK_OVERRIDE'.

include/effects/SkPixelXorXfermode.h

 /*
  * Copyright 2007 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPixelXorXfermode_DEFINED
 #define SkPixelXorXfermode_DEFINED
 
@@ skipping 11 matching lines @@
     }
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkPixelXorXfermode)
 
 protected:
     explicit SkPixelXorXfermode(SkColor opColor) : fOpColor(opColor) {}
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
     // override from SkXfermode
-    virtual SkPMColor xferColor(SkPMColor src, SkPMColor dst) const;
+    virtual SkPMColor xferColor(SkPMColor src, SkPMColor dst) const SK_OVERRIDE;
 
 private:
     SkColor fOpColor;
 
     typedef SkXfermode INHERITED;
 };
 
 #endif