VisualBenchTest: Write JSON output

platform_tools/android/apps/visualbench/src/main/java/com/skia/VisualBenchTestActivity.java

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 package com.skia;
 
 import android.app.Instrumentation;
@@ skipping 11 matching lines @@
 
     protected void setUp() throws Exception {
         super.setUp();
         mInstrumentation = getInstrumentation();
     }
 
     public void testVisualBench() throws InterruptedException {
         String pkg = getInstrumentation().getTargetContext().getPackageName();
         Intent intent = new Intent(getInstrumentation().getTargetContext(),
                                    VisualBenchActivity.class);
-        intent.putExtra("cmdLineFlags", "");
+        intent.putExtra("cmdLineFlags", "--outResultsFile /sdcard/skia_results/visualbench.json");
         mActivity = launchActivityWithIntent(pkg, VisualBenchActivity.class, intent);
 
         assertNotNull("mActivity is null", mActivity);
         Thread.sleep(5000);
         while (!mActivity.isDestroyed()) {
             Log.d("skiatest", "Waiting for subprocess to finish.");
             Thread.sleep(1000);
         }
     }
 }