Cleanup: More override fixes - another round.

BUG=skia:3075
TEST=ninja -C out/Debug
TBR=reed@google.com

Review URL: https://codereview.chromium.org/831113002
diff --git a/bench/PremulAndUnpremulAlphaOpsBench.cpp b/bench/PremulAndUnpremulAlphaOpsBench.cpp
index 6ab585e..32f749c 100644
--- a/bench/PremulAndUnpremulAlphaOpsBench.cpp
+++ b/bench/PremulAndUnpremulAlphaOpsBench.cpp
@@ -29,7 +29,7 @@
         return fName.c_str();
     }
 
-    virtual void onPreDraw() {
+    virtual void onPreDraw() SK_OVERRIDE {
         SkImageInfo info = SkImageInfo::Make(W, H, fColorType, kUnpremul_SkAlphaType);
         fBmp1.allocPixels(info);   // used in writePixels