Telemetry: make media perf tests log errors rather than timing out

tools/perf/metrics/media.js

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file contains common utilities to find video/audio elements on a page
 // and collect metrics for each.
 
 (function() {
   // MediaMetric class responsible for collecting metrics on a media element.
   // It attaches required event listeners in order to collect different metrics.
@@ skipping 105 matching lines @@
 
   HTMLMediaMetric.prototype.onEnded = function(event) {
     var time_to_end = this.playbackTimer.stop() - this.metrics['time_to_play'];
     // TODO(shadi): Measure buffering time more accurately using events such as
     // stalled, waiting, progress, etc. This works only when continuous playback
     // is used.
     this.metrics['buffering_time'] = time_to_end - this.element.duration * 1000;
   };
 
   HTMLMediaMetric.prototype.getMetrics = function() {
-    this.metrics['decoded_frame_count'] = this.element.webkitDecodedFrameCount;
-    this.metrics['dropped_frame_count'] = this.element.webkitDroppedFrameCount;
+    var decodedFrames = this.element.webkitDecodedFrameCount;
+    var droppedFrames = this.element.webkitDroppedFrameCount;
+    // Audio media does not report decoded/dropped frame count
+    if (decodedFrames != undefined)
+      this.metrics['decoded_frame_count'] = decodedFrames;
+    if (droppedFrames != undefined)
+      this.metrics['dropped_frame_count'] = droppedFrames;
     this.metrics['decoded_video_bytes'] =
-        this.element.webkitVideoDecodedByteCount;
+        this.element.webkitVideoDecodedByteCount || 0;
     this.metrics['decoded_audio_bytes'] =
-        this.element.webkitAudioDecodedByteCount;
+        this.element.webkitAudioDecodedByteCount || 0;
     return this.metrics;
   };
 
   function MediaMetric(element) {
     if (element instanceof HTMLMediaElement)
       return new HTMLMediaMetric(element);
     throw new Error('Unrecognized media element type.');
   }
 
   function Timer() {
     this.start_ = 0;
     this.start();
   }
 
   Timer.prototype = {
     start: function() {
       this.start_ = getCurrentTime();
     },
 
     stop: function() {
       // Return delta time since start in millisecs.
       return ((getCurrentTime() - this.start_)).toFixed(3);
     }
   };
 
   function checkElementIsNotBound(element) {
     if (!element)
       return;
+    if (getMediaMetric(element))
+      throw new Error('Can not create MediaMetric for same element twice.');
+  }
+
+  function getMediaMetric(element) {
     for (var i = 0; i < window.__mediaMetrics.length; i++) {
       if (window.__mediaMetrics[i].element == element)
-        throw new Error('Can not create MediaMetric for same element twice.');
+        return window.__mediaMetrics[i];
     }
+    return null;
   }
 
   function createMediaMetricsForDocument() {
     // Searches for all video and audio elements on the page and creates a
     // corresponding media metric instance for each.
     var mediaElements = document.querySelectorAll('video, audio');
     for (var i = 0; i < mediaElements.length; i++)
       window.__mediaMetrics.push(new MediaMetric(mediaElements[i]));
   }
 
@@ skipping 11 matching lines @@
   function getAllMetrics() {
     // Returns a summary (info + metrics) for all media metrics.
     var metrics = [];
     for (var i = 0; i < window.__mediaMetrics.length; i++)
       metrics.push(window.__mediaMetrics[i].getSummary());
     return metrics;
   }
 
   window.__globalCounter = 0;
   window.__mediaMetrics = [];
+  window.__getMediaMetric = getMediaMetric;
   window.__getAllMetrics = getAllMetrics;
   window.__createMediaMetricsForDocument = createMediaMetricsForDocument;
 })();