Cleanup: Another round of override fixes.

gm/peekpixels.cpp

Index: gm/peekpixels.cpp
diff --git a/gm/peekpixels.cpp b/gm/peekpixels.cpp
index 01a60c124ff70581bea3c0d0789e36043e9c21fa..b5573f3458e5f9cc5a4fbd367fdb829f4a574972 100644
--- a/gm/peekpixels.cpp
+++ b/gm/peekpixels.cpp
@@ -64,7 +64,7 @@ protected:
         }
     }
 
-    virtual uint32_t onGetFlags() const {
+    virtual uint32_t onGetFlags() const SK_OVERRIDE {
         // we explicitly test peekPixels and readPixels, neither of which
         // return something for a picture-backed canvas, so we skip that test.
         return kSkipPicture_Flag;