Telemetry media Seek action and metrics.

tools/telemetry/telemetry/page/actions/seek.js

Index: tools/telemetry/telemetry/page/actions/seek.js
diff --git a/tools/telemetry/telemetry/page/actions/seek.js b/tools/telemetry/telemetry/page/actions/seek.js
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index 0000000000000000000000000000000000000000..75d37792ba62ada64018e302d3482430c8b6a4ed
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+++ b/tools/telemetry/telemetry/page/actions/seek.js
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+// 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 seekMedia(selector, seekTime, logSeekTime) {
+    // Performs the "Seek" action on media satisfying selector.
+    var mediaElements = window.__findMediaElements(selector);
+    for (var i = 0; i < mediaElements.length; i++) {
+      seek(mediaElements[i], seekTime, logSeekTime);
+    }
+  }
+
+  function seek(element, seekTime, logSeekTime) {
+    if (element instanceof HTMLMediaElement)
+      seekHTML5Element(element, seekTime, logSeekTime);
+    else
+      console.error('Can not seek non HTML5 media elements.');
+  }
+
+  function seekHTML5Element(element, seekTime, logSeekTime) {
+    element['seeked_completed'] = false;
+    var onSeeked = function(e) {
+      element[e.type + '_completed'] = true;
+      element.removeEventListener('seeked', onSeeked);
+    };
+    function onError(e) {
+      console.error('Error playing media :' + e.type);
+    }
+    element.addEventListener('error', onError);
+    element.addEventListener('abort', onError);
+
+    if (logSeekTime) {
+      var willSeekEvent = document.createEvent('Event');
+      willSeekEvent.initEvent('willSeek', false, false);
+      willSeekEvent.seekLabel = seekTime;
+      element.dispatchEvent(willSeekEvent);
+    }
+    element.addEventListener('seeked', onSeeked);
+    try {
+      element.currentTime = seekTime;
+    } catch (err) {
+      console.error('Cannot seek with network state: ' + element.networkState);
+    }
+  }
+
+  window.__seekMedia = seekMedia;
+})();