Wire up configurations properly in VisualBench

tools/VisualBench/VisualFlags.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "VisualFlags.h"
 
-DEFINE_int32(msaa, 0, "Number of msaa samples.");
-DEFINE_bool(nvpr, false, "Run in NVPR mode?");
+SkString Configs::Config::humanReadable() const {
+    SkString out;
+    switch (fType) {
+        case kGpu_Type:
+            out.append("gpu");
+            break;
+        case kMsaa_Type:
+            out.appendf("msaa_%d", fNumSamples);
+            break;
+        case kNvpr_Type:
+            out.appendf("nvprmsaa_%d", fNumSamples);
+            break;
+        case kCpu_Type:
+            out.append("cpu");
+            break;
+    }
+    return out;
+}
+
+DEFINE_string(config, "gpu", "Options: "
+              "cpu gpu msaa16 msaa4 nvprmsaa16 nvprmsaa4");