Expand VisualBench to a real benching tool

tools/VisualBench.h

Index: tools/VisualBench.h
diff --git a/tools/VisualBench.h b/tools/VisualBench.h
index d9e0b508669c34ad799f9b8e5adf49495cdb0319..9fd733dcf147636a1d9f3ccdda533545d974b536 100644
--- a/tools/VisualBench.h
+++ b/tools/VisualBench.h
@@ -38,12 +38,20 @@ protected:
 private:
     void setTitle();
     bool setupBackend();
+    void resetContext();
     void setupRenderTarget();
     bool onHandleChar(SkUnichar unichar) override;
+    void timeFrame(SkCanvas*);
+    void printStats();
+
+    struct Timing {
+        SkString fName;
+        SkTArray<double> fMeasurements;
+    };
 
-    int fCurrentLoops;
     int fCurrentPicture;
     int fCurrentFrame;
+    SkTArray<Timing> fTimings;
     SkTArray<SkPicture*> fPictures;
 
     // support framework