Implement the new wallpaper manager launcher window.

chrome/browser/resources/chromeos/wallpaper_manager/js/mock_chrome.js

Index: chrome/browser/resources/chromeos/wallpaper_manager/js/mock_chrome.js
diff --git a/chrome/browser/resources/chromeos/wallpaper_manager/js/mock_chrome.js b/chrome/browser/resources/chromeos/wallpaper_manager/js/mock_chrome.js
new file mode 100644
index 0000000000000000000000000000000000000000..3d0ce8a384d66a80d9760ae10d1304195a9d8a95
--- /dev/null
+++ b/chrome/browser/resources/chromeos/wallpaper_manager/js/mock_chrome.js
@@ -0,0 +1,15 @@
+// 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.
+
+/**
+ * Mock the background page functions for use in the harness.
+ */
+document.querySelector('#dialog').contentWindow.chrome.extension = {
+  getBackgroundPage: function() {
+    return {'windowStateManager': {
+      saveStates: function() {},
+      restoreStates: function() {}
+    }};
+  }
+};