flag to use const& instead of const* for src-rect

BUG=skia:

Review URL: https://codereview.chromium.org/1272713005
diff --git a/bench/BitmapRectBench.cpp b/bench/BitmapRectBench.cpp
index 061bfe8..d95d753 100644
--- a/bench/BitmapRectBench.cpp
+++ b/bench/BitmapRectBench.cpp
@@ -96,7 +96,7 @@
         paint.setAlpha(fAlpha);
 
         for (int i = 0; i < loops; i++) {
-            canvas->drawBitmapRect(fBitmap, &fSrcR, fDstR, &paint,
+            canvas->drawBitmapRect(fBitmap, fSrcR, fDstR, &paint,
                                    SkCanvas::kStrict_SrcRectConstraint);
         }
     }