MD-Settings: convert cr-settings-prefs to a singleton model

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

Index: chrome/browser/resources/settings/prefs/prefs_types.js
diff --git a/chrome/browser/resources/settings/prefs/prefs_types.js b/chrome/browser/resources/settings/prefs/prefs_types.js
index 3ac53ba967be5c3193a1b6b8a7087894c368ba4d..a2eb3763e5ceaef4a72718dc336eca8690d81906 100644
--- a/chrome/browser/resources/settings/prefs/prefs_types.js
+++ b/chrome/browser/resources/settings/prefs/prefs_types.js
@@ -6,22 +6,44 @@
  * @fileoverview Types for CrSettingsPrefsElement.
  */
 
-/** @type {{INITIALIZED: string, isInitialized: boolean}} */
-var CrSettingsPrefs;
+/**
+ * Global state for prefs status.
+ */
+var CrSettingsPrefs = (function() {
+  var resolveInitialized;
 
-// TODO(michaelpg): provide a Promise for initialization.
-if (CrSettingsPrefs === undefined) {
-  CrSettingsPrefs = {
+  return {
     /**
-     * The name of the event fired when prefs have been fetched and initialized.
-     * @const {string}
+     * Set to true when all settings have been initialized.
+     * @type {boolean}
      */
-    INITIALIZED: 'cr-settings-prefs-initialized',
+    isInitialized: false,
 
     /**
-     * Global boolean set to true when all settings have been initialized.
-     * @type {boolean}
+     * Promise to be resolved when all settings have been initialized.
+     * @type {Promise}
      */
-    isInitialized: false,
+    initialized: Promise.resolve(),
+
+    /**
+     * Rresolves the CrSettingsPrefs.initialized promise.
+     */
+    setInitialized: function() {
+      CrSettingsPrefs.isInitialized = true;
+      resolveInitialized();
+    },
+
+    /**
+     * Called to set up the promise and resolve methods, and to restore
+     * state for testing.
+     */
+    reset: function() {
+      CrSettingsPrefs.initialized = new Promise(function(resolve) {
+        resolveInitialized = resolve;
+      });
+      CrSettingsPrefs.isInitialized = false;
+    },
   };
-}
+})();
+
+CrSettingsPrefs.reset();