Add data reduction proxy integration tests for video compression.

tools/chrome_proxy/integration_tests/videowrapper.js

+// Copyright 2013 The Chromium Authors. All rights reserved.

[bolian, 2015/04/10 21:00:03]

2015

[Tom Bergan, 2015/04/10 21:14:46]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This script finds the first video element on a page and collect metrics
+// for that element. This is based on src/tools/perf/metrics/media.js.
+
+(function() {
+  // VideoWrapper attaches event listeners to collect metrics.
+  // The constructor starts playing the video.
+  function VideoWrapper(element) {
+    if (!(element instanceof HTMLVideoElement))
+      throw new Error('Unrecognized video element type ' + element);
+    metrics['ready'] = false;
+    this.element = element;
+    element.loop = false;
+    // Set the basic event handlers for this HTML5 video element.
+    this.element.addEventListener('loadedmetadata', this.onLoaded.bind(this));
+    this.element.addEventListener('canplay', this.onCanplay.bind(this));
+    this.element.addEventListener('ended', this.onEnded.bind(this));
+    this.playbackTimer = new Timer();
+    element.play()
+  }
+
+  VideoWrapper.prototype.onLoaded = function(e) {
+    if (this.element.readyState == HTMLMediaElement.HAVE_NOTHING) {
+      return
+    }
+    metrics['ready'] = true;
+    metrics['video_height'] = this.element.videoHeight;
+    metrics['video_width'] = this.element.videoWidth;
+    metrics['video_duration'] = this.element.duration;
+    window.__chromeProxyVideoLoaded = true;
+  };
+
+  VideoWrapper.prototype.onCanplay = function(event) {
+    metrics['time_to_play_ms'] = this.playbackTimer.stop();
+  };
+
+  VideoWrapper.prototype.onEnded = function(event) {
+    var time_to_end = this.playbackTimer.stop() - metrics['time_to_play_ms'];
+    metrics['buffering_time_ms'] = time_to_end - this.element.duration * 1000;
+    metrics['decoded_audio_bytes'] = this.element.webkitAudioDecodedByteCount;
+    metrics['decoded_video_bytes'] = this.element.webkitVideoDecodedByteCount;
+    metrics['decoded_frames'] = this.element.webkitDecodedFrameCount;
+    metrics['dropped_frames'] = this.element.webkitDroppedFrameCount;
+    window.__chromeProxyVideoEnded = true;
+  };
+
+  function MediaMetric(element) {
+    if (element instanceof HTMLMediaElement)
+      return new VideoWrapper(element);
+    throw new Error('Unrecognized media element type.');
+  }
+
+  function Timer() {
+    this.start_ = 0;

[bolian, 2015/04/10 21:00:03]

delete this line?

[Tom Bergan, 2015/04/10 21:14:46]

I think uninitialized fields default to null? See line 68

[bolian, 2015/04/10 21:46:29]

I mean this.start() will initialize it, so we don't need this.

[Tom Bergan, 2015/04/10 23:41:04]

Done.

+    this.start();
+  }
+
+  Timer.prototype = {
+    start: function() {
+      this.start_ = getCurrentTime();
+    },
+
+    stop: function() {
+      // Return delta time since start in millisecs.

[bolian, 2015/04/10 21:00:03]

this is in seconds but with precision to ms?

[Tom Bergan, 2015/04/10 21:14:46]

window.performance.now returns a double in ms. This math rounds to the nearest
.001ms. Copied this from media.js, happy to change it if you like.

[bolian, 2015/04/10 21:46:29]

ok. lg as is.

[Tom Bergan, 2015/04/10 23:41:04]

Acknowledged.

+      return Math.round((getCurrentTime() - this.start_) * 1000) / 1000;
+    }
+  };
+
+  function getCurrentTime() {
+    if (window.performance)

[bolian, 2015/04/10 21:00:03]

For chrome only, we don't this complexity?

[Tom Bergan, 2015/04/10 21:14:46]

I don't know why all this code is here. I copied from media.js (see comments at
the top). I think all the Chromes that we care about support
window.performance.now, but I don't know. Scott, do you know?

[bolian, 2015/04/10 21:46:29]

Probably they copy from general js library to support multiple browsers. I think
we should just use  preformance.now.

[sclittle, 2015/04/10 23:01:49]

Either way seems fine to me, but I'd recommend keeping it as-is; it's more
consistent with media.js from which it was copied. Chrome has supported
window.performance.now to some degree since M24 or so, so we shouldn't have any
problems there.

[Tom Bergan, 2015/04/10 23:41:04]

Acknowledged.

+      return (performance.now ||
+              performance.mozNow ||
+              performance.msNow ||
+              performance.oNow ||
+              performance.webkitNow).call(window.performance);
+    else
+      return Date.now();
+  }
+
+  function createVideoWrappersForDocument() {
+    var videos = document.querySelectorAll('video');
+    switch (videos.length) {
+    case 0:
+      throw new Error('Page has no videos.');
+    case 1:
+      break;
+    default:
+      throw new Error('Page too many videos: ' + videos.length.toString());
+    }
+    new VideoWrapper(videos[0])
+  }
+
+  metrics = {};
+  window.__chromeProxyCreateVideoWrappers = createVideoWrappersForDocument;
+  window.__chromeProxyVideoMetrics = metrics;
+  window.__chromeProxyVideoLoaded = false;
+  window.__chromeProxyVideoEnded = false;
+})();