Major bench refactoring.

bench/MergeBench.cpp

Index: bench/MergeBench.cpp
diff --git a/bench/MergeBench.cpp b/bench/MergeBench.cpp
index 992507d9b5dc76d77e3f9a1ef565348ff7e73175..98a918af0234a9448ec30b228ac96d6034b9cd05 100644
--- a/bench/MergeBench.cpp
+++ b/bench/MergeBench.cpp
@@ -38,7 +38,9 @@ protected:
                               SkRect::MakeWH(FILTER_WIDTH_LARGE, FILTER_HEIGHT_LARGE);
         SkPaint paint;
         paint.setImageFilter(mergeBitmaps())->unref();
-        canvas->drawRect(r, paint);
+        for (int i = 0; i < this->getLoops(); i++) {
+            canvas->drawRect(r, paint);
+        }
     }
 
 private: