Telemetry media_measurement plus play action and tests.

tools/telemetry/telemetry/page/actions/play.js

Index: tools/telemetry/telemetry/page/actions/play.js
diff --git a/tools/telemetry/telemetry/page/actions/play.js b/tools/telemetry/telemetry/page/actions/play.js
new file mode 100644
index 0000000000000000000000000000000000000000..3ff8f8f6a1bf964fce6fdf1b902291fa231d7232
--- /dev/null
+++ b/tools/telemetry/telemetry/page/actions/play.js
@@ -0,0 +1,76 @@
+// Copyright (c) 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 performs actions on media elements.
+(function() {
+  function findMediaElements(selector) {
+    // Returns elements matching the selector, otherwise returns the first video
+    // or audio tag element that can be found.
+    // If selector == 'all', returns all media elements.
+    if (selector == 'all') {
+      return document.querySelectorAll('video, audio');
+    } else if (selector) {
+      return document.querySelectorAll(selector);
+    } else {
+      var media = document.getElementsByTagName('video');
+      if (media.length > 0) {
+        return [media[0]];
+      } else {
+        media = document.getElementsByTagName('audio');
+        if (media.length > 0) {
+          return [media[0]];
+        }
+      }
+    }
+    console.error('Could not find any media elements matching: ' + selector);
+    return [];
+  }
+
+  function playMedia(selector) {
+    // Performs the "Play" action on media satisfying selector.
+    var mediaElements = findMediaElements(selector);
+    for (var i = 0; i < mediaElements.length; i++) {
+      console.log('Playing element: ' + mediaElements[i].src);
+      play(mediaElements[i]);
+    }
+  }
+
+  function play(element) {
+    if (element instanceof HTMLMediaElement)
+      playHTML5Element(element);
+    else
+      console.error('Can not play non HTML5 media elements.');
+  }
+
+  function playHTML5Element(element) {
+    function logEventHappened(e) {
+      element[e.type + '_completed'] = true;
+    }
+    function onError(e) {
+      console.error('Error playing media :' + e.type);
+    }
+    element.addEventListener('playing', logEventHappened);
+    element.addEventListener('ended', logEventHappened);
+    element.addEventListener('error', onError);
+    element.addEventListener('abort', onError);
+
+    var willPlayEvent = document.createEvent('Event');
+    willPlayEvent.initEvent('willPlay', false, false);
+    element.dispatchEvent(willPlayEvent);
+    element.play();
+  }
+
+  function hasEventCompleted(selector, event_name) {
+    // Return true if the event_name fired for media satisfying the selector.
+    var mediaElements = findMediaElements(selector);
+    for (var i = 0; i < mediaElements.length; i++) {
+      if (!mediaElements[i][event_name + '_completed'])
+        return false;
+    }
+    return true;
+  }
+
+  window.__playMedia = playMedia;
+  window.__hasEventCompleted = hasEventCompleted;
+})();