Fix up all the easy virtual ... SK_OVERRIDE cases.

src/gpu/GrDrawTarget.h

Index: src/gpu/GrDrawTarget.h
diff --git a/src/gpu/GrDrawTarget.h b/src/gpu/GrDrawTarget.h
index b1d1492764212ea2a685e9b1178a79dfa7634991..0e211ba85d44ecca6170f02f130222f19a7dfa39 100644
--- a/src/gpu/GrDrawTarget.h
+++ b/src/gpu/GrDrawTarget.h
@@ -837,7 +837,7 @@ public:
      * Release any resources that are cached but not currently in use. This
      * is intended to give an application some recourse when resources are low.
      */
-    virtual void purgeResources() SK_OVERRIDE {
+    void purgeResources() SK_OVERRIDE {
         // The clip mask manager can rebuild all its clip masks so just
         // get rid of them all.
         fClipMaskManager.purgeResources();