benchmarks: Avoid brackets and commas in test names.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2295483002

Review-Url: https://codereview.chromium.org/2295483002
diff --git a/bench/BlurRoundRectBench.cpp b/bench/BlurRoundRectBench.cpp
index ef88422..713996c 100644
--- a/bench/BlurRoundRectBench.cpp
+++ b/bench/BlurRoundRectBench.cpp
@@ -25,7 +25,7 @@
 public:
     BlurRoundRectBench(int width, int height, int cornerRadius)
         : fName("blurroundrect") {
-        fName.appendf("_WH[%ix%i]_cr[%i]", width, height, cornerRadius);
+        fName.appendf("_WH_%ix%i_cr_%i", width, height, cornerRadius);
         SkRect r = SkRect::MakeWH(SkIntToScalar(width), SkIntToScalar(height));
         fRRect.setRectXY(r, SkIntToScalar(cornerRadius), SkIntToScalar(cornerRadius));
     }