Added background page loader component extension.

chrome/browser/resources/chromeos/backloader/scripts/background.js

+// Copyright (c) 2012 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.
+
+function Loader(pages) {
+  this.pages_ = pages;
+  this.pages_loaded_ = false;
+  this.loaded_count_ = false;
+}
+
+// Global instance.
+Loader.instance_ = null;
+// Alarm name.
+Loader.ALARM_NAME = 'BkgLoaderAlarm';
+// Initial delay.
+Loader.DELAY_IN_MINUTES = 1;
+// Periodic wakeup delay.
+Loader.PERIOD_IN_MINUTES = 60;
+// Delayed closing of the background page once when all iframes are loaded.
+Loader.UNLOAD_DELAY_IN_MS = 10000;
+
+// static.
+Loader.getInstance = function() {
+  if (!Loader.instance_)
+    Loader.instance_ = new Loader(g_pages);
+
+  return Loader.instance_;
+};
+
+// Alarm event handler.
+Loader.onAlarm = function(alarm) {
+  Loader.getInstance().onAlarm_(alarm);
+};
+
+// Loader start up. Kicks off alarm initialization if needed.
+Loader.prototype.start = function() {
+  console.log('Starting background loader');
+  chrome.alarms.onAlarm.addListener(Loader.onAlarm);
+  // Check if this alarm already exists, if not then create it.
+  chrome.alarms.get(Loader.ALARM_NAME, function(alarm) {
+    if (!alarm) {
+      console.log('Creating alarm!');
+      chrome.alarms.create(Loader.ALARM_NAME,
+                           {delayInMinutes: Loader.DELAY_IN_MINUTES,
+                            periodInMinutes: Loader.PERIOD_IN_MINUTES});
+      window.close();
+      return;
+    }
+    console.log('Has alarm already!');
+  }.bind(this));
+};
+
+Loader.prototype.onAlarm_ = function(alarm) {
+  console.log('Got alarm ' + alarm.name);
+  if (this.pages_loaded_) {
+    console.log('Pages already loaded!');
+    return;
+  }
+  for (i = 0; i < this.pages_.length; i++) {
+    this.loadPage_(i, this.pages_[i]);
+  }
+  this.pages_loaded_ = true;
+};
+
+Loader.prototype.loadPage_ = function(index, pageUrl) {
+  var iframe = document.createElement('iframe');
+  iframe.onload = function() {
+    this.loaded_count_++;
+    console.log('Total ' + this.loaded_count_ + ' pages loaded.');
+    if (this.loaded_count_ < this.pages_.length)
+      return;
+
+    console.log('All pages loaded!');
+    // Delay closing.
+    setInterval(function() {
+      console.log('Closing background page.');
+      window.close();
+    }.bind(this), Loader.UNLOAD_DELAY_IN_MS);
+  }.bind(this);
+  iframe.src = pageUrl;
+  iframe.name = 'frame' + index;
+  document.body.appendChild(iframe);
+};
+
+Loader.getInstance().start();