Major bench refactoring.
   - Use FLAGS_.
   - Remove outer repeat loop.
   - Tune inner loop automatically.

BUG=skia:1590
R=epoger@google.com, scroggo@google.com

Review URL: https://codereview.chromium.org/23478013

git-svn-id: http://skia.googlecode.com/svn/trunk@11187 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/bench/BitmapRectBench.cpp b/bench/BitmapRectBench.cpp
index c147da2..f917445 100644
--- a/bench/BitmapRectBench.cpp
+++ b/bench/BitmapRectBench.cpp
@@ -47,7 +47,6 @@
     SkRect      fSrcR, fDstR;
     static const int kWidth = 128;
     static const int kHeight = 128;
-    enum { N = SkBENCHLOOP(300) };
 public:
     BitmapRectBench(void* param, U8CPU alpha, bool doFilter, bool slightMatrix) : INHERITED(param) {
         fAlpha = SkToU8(alpha);
@@ -93,7 +92,7 @@
         paint.setFilterBitmap(fDoFilter);
         paint.setAlpha(fAlpha);
 
-        for (int i = 0; i < N; i++) {
+        for (int i = 0; i < this->getLoops(); i++) {
             canvas->drawBitmapRectToRect(fBitmap, &fSrcR, fDstR, &paint);
         }
     }