[Telemetry] Move page quiescence test to WebContents

tools/perf/metrics/speedindex.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.
-
-'use strict';
-
-/**
- * @fileoverview This file provides a JavaScript helper function that
- * determines when the last resource was received.
- */
-(function() {
-
-  // Set the Resource Timing interface functions that will be used below
-  // to use whatever version is available currently regardless of vendor
-  // prefix.
-  window.performance.clearResourceTimings =
-      (window.performance.clearResourceTimings     ||
-       window.performance.mozClearResourceTimings  ||
-       window.performance.msClearResourceTimings   ||
-       window.performance.oClearResourceTimings    ||
-       window.performance.webkitClearResourceTimings);
-
-  window.performance.getEntriesByType =
-      (window.performance.getEntriesByType     ||
-       window.performance.mozGetEntriesByType  ||
-       window.performance.msGetEntriesByType   ||
-       window.performance.oGetEntriesByType    ||
-       window.performance.webkitGetEntriesByType);
-
-  // This variable will available to the function below and it will be
-  // persistent across different function calls. It stores the last
-  // entry in the list of PerformanceResourceTiming objects returned by
-  // window.performance.getEntriesByType('resource').
-  //
-  // The reason for doing it this way is because the buffer for
-  // PerformanceResourceTiming objects has a limit, and once it's full,
-  // new entries are not added. We're only interested in the last entry,
-  // so we can clear new entries when they're added.
-  var lastEntry = null;
-
-  /**
-   * This method uses the Resource Timing interface, which is described at
-   * http://www.w3.org/TR/resource-timing/. It provides information about
-   * timings for resources such as images and script files, and it includes
-   * resources requested via XMLHttpRequest.
-   *
-   * @return {number} The time since either the load event, or the last
-   *   the last resource was received after the load event. If the load
-   *   event hasn't yet happened, return 0.
-   */
-  window.timeSinceLastResponseAfterLoadMs = function() {
-    if (window.document.readyState !== 'complete') {
-      return 0;
-    }
-
-    var resourceTimings = window.performance.getEntriesByType('resource');
-    if (resourceTimings.length > 0) {
-      lastEntry = resourceTimings.pop();
-      window.performance.clearResourceTimings();
-    }
-
-    // The times for performance.now() and in the PerformanceResourceTiming
-    // objects are all in milliseconds since performance.timing.navigationStart,
-    // so we must also get load time in the same terms.
-    var timing = window.performance.timing;
-    var loadTime = timing.loadEventEnd - timing.navigationStart;
-
-    // If there have been no resource timing entries, or the last entry was
-    // before the load event, then return the time since the load event.
-    if (!lastEntry || lastEntry.responseEnd < loadTime) {
-      return window.performance.now() - loadTime;
-    }
-    return window.performance.now() - lastEntry.responseEnd;
-  }
-
-})();