Update VR latency summary format

Updates the VR motion-to-photon latency test's output.json format to
match the newer version used by Telemetry and other script tests. This
is necessary because the chromium_tests recipe was recently updated to
assume that a test is disabled if the results don't include the "tests"
key, which is causing results to not be uploaded to the dashboard.

Bug: 
Change-Id: I15102724d3a688bd80b87e583c85dd159cc9feba
Reviewed-on: https://chromium-review.googlesource.com/662879Reviewed-by: Christopher Grant <cjgrant@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501345}

chrome/test/vr/perf/latency/webvr_latency_test.py

@@ -102,6 +102,7 @@ class WebVrLatencyTest(object):
     self._test_urls = args.urls or DEFAULT_URLS
     assert (self._num_samples > 0),'Number of samples must be greater than 0'
     self._test_results = {}
+    self._test_name = 'vr_perf.motopho_latency'
 
     # Connect to the Arduino that drives the servos.
     devices = GetTtyDevices(r'ttyACM\d+', [0x2a03, 0x2341])
@@ -144,6 +145,7 @@ class WebVrLatencyTest(object):
       if motopho_thread.failed_iteration:
         num_retries += 1
         if num_retries > MOTOPHO_THREAD_RETRIES:
+          self._ReportSummaryResult(False, url)
           raise RuntimeError(
               'Motopho thread failed more than %d times, aborting' % (
                   MOTOPHO_THREAD_RETRIES))
@@ -151,6 +153,7 @@ class WebVrLatencyTest(object):
       else:
         samples_obtained += 1
       time.sleep(1)
+    self._ReportSummaryResult(True, url)
     self._StoreResults(motopho_thread.latencies, motopho_thread.correlations,
                        url)
     # Leaving old threads around shouldn't cause issues, but clean up just in
@@ -160,6 +163,19 @@ class WebVrLatencyTest(object):
     if motopho_thread.isAlive():
       logging.warning('Motopho thread failed to terminate.')
 
+  def _ReportSummaryResult(self, passed, url):
+    """Stores pass/fail results for the summary output JSON file.
+
+    Args:
+      passed: Boolean, whether the test passed or not
+      url: The URL that was being tested
+    """
+    self._results_summary[url] = {
+        'actual': 'PASS' if passed else 'FAIL',
+        'expected': 'PASS',
+        'is_unexpected': not passed,
+    }
+
   def _StoreResults(self, latencies, correlations, url):
     """Temporarily stores the results of a test.
 
@@ -246,7 +262,7 @@ class WebVrLatencyTest(object):
 
     results = {
       'format_version': '1.0',
-      'benchmark_name': 'vr_perf.motopho_latency',
+      'benchmark_name': self._test_name,
       'benchmark_description': 'Measures the motion-to-photon latency of WebVR',
       'charts': charts,
     }

chrome/test/vr/perf/vr_perf_test.py

@@ -5,6 +5,7 @@
 import json
 import logging
 import subprocess
+import time
 
 class VrPerfTest(object):
   """Base class for all non-Telemetry VR perf tests.
@@ -16,6 +17,8 @@ class VrPerfTest(object):
     super(VrPerfTest, self).__init__()
     self._args = args
     self._test_urls = []
+    self._results_summary = {}
+    self._test_name = ''
 
   def RunTests(self):
     """Runs some test on all the URLs provided to the test on creation.
@@ -92,6 +95,24 @@ class VrPerfTest(object):
             self._args.isolated_script_test_output):
       logging.warning('Isolated script output file not specified, not saving')
       return
+
+    results_summary = {
+        'interrupted': False,
+        'path_delimiter': '/',
+        'seconds_since_epoch': time.time(),
+        'version': 3,
+        'tests': {
+            self._test_name: self._results_summary
+        }
+    }
+
+    failure_counts = {}
+    for _, results in self._results_summary.iteritems():
+      if results['actual'] in failure_counts:
+        failure_counts[results['actual']] += 1
+      else:
+        failure_counts[results['actual']] = 1
+    results_summary['num_failures_by_type'] = failure_counts
+
     with file(self._args.isolated_script_test_output, 'w') as outfile:
-      # TODO(bsheedy): Actually check failures/validity
-      json.dump({'failures': [], 'valid': True}, outfile)
+      json.dump(results_summary, outfile)