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/MutexBench.cpp b/bench/MutexBench.cpp
index d96f3f6..5a7058d 100644
--- a/bench/MutexBench.cpp
+++ b/bench/MutexBench.cpp
@@ -8,10 +8,6 @@
 #include "SkThread.h"
 
 class MutexBench : public SkBenchmark {
-    enum {
-        N = SkBENCHLOOP(80),
-        M = SkBENCHLOOP(200)
-    };
 public:
     MutexBench(void* param) : INHERITED(param) {
         fIsRendering = false;
@@ -22,12 +18,10 @@
     }
 
     virtual void onDraw(SkCanvas*) {
-        for (int i = 0; i < N; i++) {
-            SK_DECLARE_STATIC_MUTEX(mu);
-            for (int j = 0; j < M; j++) {
-                mu.acquire();
-                mu.release();
-            }
+        SK_DECLARE_STATIC_MUTEX(mu);
+        for (int i = 0; i < this->getLoops(); i++) {
+            mu.acquire();
+            mu.release();
         }
     }