Implement a benchmark for GrResourceCache

bench/SkipZeroesBench.cpp

Index: bench/SkipZeroesBench.cpp
diff --git a/bench/SkipZeroesBench.cpp b/bench/SkipZeroesBench.cpp
index fc2f060a353b10347aaf427e7da7a330f4345e47..b0e363051d5e0225e0db28dbbb640962ef0efedc 100644
--- a/bench/SkipZeroesBench.cpp
+++ b/bench/SkipZeroesBench.cpp
@@ -33,7 +33,10 @@ public:
         } else {
             fName.append("_write_zeroes");
         }
-        fIsRendering = false;
+    }
+
+    virtual bool isSuitableFor(Backend backend) SK_OVERRIDE {
+        return backend == kNonRendering_Backend;
     }
 
 protected: