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/ReadPixBench.cpp b/bench/ReadPixBench.cpp
index 66db2eb..505ff32 100644
--- a/bench/ReadPixBench.cpp
+++ b/bench/ReadPixBench.cpp
@@ -45,9 +45,11 @@
 
         bitmap.setConfig(SkBitmap::kARGB_8888_Config, kWindowSize, kWindowSize);
 
-        for (int x = 0; x < kNumStepsX; ++x) {
-            for (int y = 0; y < kNumStepsY; ++y) {
-                canvas->readPixels(&bitmap, x * offX, y * offY);
+        for (int i = 0; i < this->getLoops(); i++) {
+            for (int x = 0; x < kNumStepsX; ++x) {
+                for (int y = 0; y < kNumStepsY; ++y) {
+                    canvas->readPixels(&bitmap, x * offX, y * offY);
+                }
             }
         }
     }