Add Polymer tests for cr-settings-prefs

chrome/browser/resources/settings/prefs/prefs.js

Index: chrome/browser/resources/settings/prefs/prefs.js
diff --git a/chrome/browser/resources/settings/prefs/prefs.js b/chrome/browser/resources/settings/prefs/prefs.js
index 98c82f78b5c4543a20fc1dd601e5bfabe98b010c..9b311e84aa6336970fb326524d2f41cabd38ce0b 100644
--- a/chrome/browser/resources/settings/prefs/prefs.js
+++ b/chrome/browser/resources/settings/prefs/prefs.js
@@ -107,13 +107,19 @@ function ListPrefWrapper(prefObj) {
       'prefsChanged_(prefs.*)',
     ],
 
+    settingsApi_: chrome.settingsPrivate,

[michaelpg, 2015/09/05 07:11:59]

is this type-able? {chrome.settingsPrivate} itself isn't a type.

+
     /** @override */
     created: function() {
+      // Set window.mockApi to pass a custom settings API, i.e. for tests.
+      // TODO(michaelpg): don't use a global.
+      if (window.mockApi)
+        this.settingsApi_ = window.mockApi;
       CrSettingsPrefs.isInitialized = false;
 
-      chrome.settingsPrivate.onPrefsChanged.addListener(
+      this.settingsApi_.onPrefsChanged.addListener(
           this.onSettingsPrivatePrefsChanged_.bind(this));
-      chrome.settingsPrivate.getAllPrefs(
+      this.settingsApi_.getAllPrefs(
           this.onSettingsPrivatePrefsFetched_.bind(this));
     },
 
@@ -127,6 +133,9 @@ function ListPrefWrapper(prefObj) {
         return;
 
       var key = this.getPrefKeyFromPath_(change.path);
+      if (!key)
+        return;
+
       var prefWrapper = this.prefWrappers_[key];
       if (!prefWrapper)
         return;
@@ -140,7 +149,7 @@ function ListPrefWrapper(prefObj) {
       if (prefWrapper.equals(this.createPrefWrapper_(prefObj)))
         return;
 
-      chrome.settingsPrivate.setPref(
+      this.settingsApi_.setPref(
           key,
           prefObj.value,
           /* pageId */ '',
@@ -182,7 +191,7 @@ function ListPrefWrapper(prefObj) {
 
       // Get the current pref value from chrome.settingsPrivate to ensure the
       // UI stays up to date.
-      chrome.settingsPrivate.getPref(key, function(pref) {
+      this.settingsApi_.getPref(key, function(pref) {
         this.updatePrefs_([pref]);
       }.bind(this));
     },
@@ -229,8 +238,8 @@ function ListPrefWrapper(prefObj) {
     },
 
     /**
-     * Sets or updates the pref denoted by newPrefObj.key in the publicy exposed
-     * |prefs| property.
+     * Sets or updates the pref denoted by newPrefObj.key in the publicly
+     * exposed |prefs| property.
      * @param {chrome.settingsPrivate.PrefObject} newPrefObj The pref object to
      *     update the pref with.
      * @private