Implement a benchmark for GrResourceCache

bench/MatrixBench.cpp

Index: bench/MatrixBench.cpp
diff --git a/bench/MatrixBench.cpp b/bench/MatrixBench.cpp
index 796c7e5287fa0c1ff41f849f89454cd79a970113..c2d68b5b85d9bdd22422b34e2faa4f7700e68659 100644
--- a/bench/MatrixBench.cpp
+++ b/bench/MatrixBench.cpp
@@ -16,7 +16,10 @@ class MatrixBench : public SkBenchmark {
 public:
     MatrixBench(const char name[])  {
         fName.printf("matrix_%s", name);
-        fIsRendering = false;
+    }
+
+    virtual bool isSuitableFor(Backend backend) SK_OVERRIDE {
+        return backend == kNonRendering_Backend;
     }
 
     virtual void performTest() = 0;