Added mock_xhr module w/ unit tests.

remoting/webapp/base/js/base.js

 // Copyright 2014 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.
 
 /**
  * @fileoverview
  * A module that contains basic utility components and methods for the
  * chromoting project
  *
  */
@@ skipping 197 matching lines @@
  *   (e.g. undefined, NaN).
  */
 base.deepCopy = function(value) {
   try {
     return JSON.parse(JSON.stringify(value));
   } catch (e) {}
   return null;
 };
 
 /**
+ * Returns a copy of the input object with all null/undefined fields

[John Williams, 2015/04/02 23:57:05]

Moved from xhr.js.

+ * removed.  Returns an empty object for a null/undefined input.
+ *
+ * @param {Object<string,?T>|undefined} input
+ * @return {!Object<string,T>}
+ * @template T
+ */
+base.copyWithoutNullFields = function(input) {
+  /** @const {!Object} */
+  var result = {};
+  if (input) {
+    for (var field in input) {
+      var value = /** @type {*} */ (input[field]);
+      if (value != null) {

[Jamie, 2015/04/03 01:45:56]

Is "value != null" the same as "value !== null && value !== undefined"? It
won't, for example, fail for 0 or ''?

[John Williams, 2015/04/04 01:40:25]

Correct.

+        result[field] = value;
+      }
+    }
+  }
+  return result;
+};
+
+/**
  * @type {boolean|undefined}
  * @private
  */
 base.isAppsV2_ = undefined;
 
 /**
  * @return {boolean} True if this is a v2 app; false if it is a legacy app.
  */
 base.isAppsV2 = function() {
   if (base.isAppsV2_ === undefined) {
@@ skipping 477 matching lines @@
  */
 base.resizeWindowToContent = function() {
   var appWindow = chrome.app.window.current();
   var outerBounds = appWindow.outerBounds;
   var borderY = outerBounds.height - appWindow.innerBounds.height;
   appWindow.resizeTo(outerBounds.width, document.body.clientHeight + borderY);
   // Sometimes, resizing the window causes its position to be reset to (0, 0),
   // so restore it explicitly.
   appWindow.moveTo(outerBounds.left, outerBounds.top);
 };