Allow users to add third-party VPNs from the settings page

chrome/browser/resources/options/chromeos/vpn_providers.js

Index: chrome/browser/resources/options/chromeos/vpn_providers.js
diff --git a/chrome/browser/resources/options/chromeos/vpn_providers.js b/chrome/browser/resources/options/chromeos/vpn_providers.js
index 911c68487fbf67238d92644ad4eb93e2329bdd87..661a62c126196ecc063b6fafb2de4682c8e451b0 100644
--- a/chrome/browser/resources/options/chromeos/vpn_providers.js
+++ b/chrome/browser/resources/options/chromeos/vpn_providers.js
@@ -26,6 +26,33 @@ cr.define('options', function() {
     providers_: [],
 
     /**
+     * Observers who will be notified when the list of VPN providers changes.
+     * @type {!Array<!function()>}
+     */
+    observers_: [],
+
+    /**
+     * The VPN providers enabled in the primary user's profile.
+     * @type {!Array<{name: string, extensionID: ?string}>}
+     */
+    get providers() {
+      return this.providers_;
+    },
+    set providers(providers) {
+      this.providers_ = providers;
+      for (var i = 0; i < this.observers_.length; ++i)
+        this.observers_[i]();

[michaelpg, 2015/03/19 19:48:28]

What would happen if an observer tried to set providers?

[bartfab (slow), 2015/03/20 00:10:25]

As discussed, I added a comment warning about this.

+    },
+
+    /**
+     * Adds an observer to be notified when the list of VPN providers changes.
+     * @param {!function()} observer The observer to add.
+     */
+    addObserver: function(observer) {
+      this.observers_.push(observer);
+    },
+
+    /**
      * Formats a network name for display purposes. If the network belongs to
      * a third-party VPN provider, the provider name is added to the network
      * name.
@@ -50,12 +77,20 @@ cr.define('options', function() {
   };
 
   /**
+   * Adds an observer to be notified when the list of VPN providers changes.

[michaelpg, 2015/03/19 19:48:28]

nit: s/notified/called

[bartfab (slow), 2015/03/20 00:10:25]

Done.

+   * @param {!function()} observer The observer to add.
+   */
+  VPNProviders.addObserver = function(observer) {
+    VPNProviders.getInstance().addObserver(observer);
+  };
+
+  /**
    * Returns the list of VPN providers enabled in the primary user's profile.
    * @return {!Array<{name: string, extensionID: ?string}>} The list of VPN
    *     providers enabled in the primary user's profile.
    */
   VPNProviders.getProviders = function() {
-    return VPNProviders.getInstance().providers_;
+    return VPNProviders.getInstance().providers;
   };
 
   /**
@@ -64,7 +99,7 @@ cr.define('options', function() {
    *     of VPN providers enabled in the primary user's profile.
    */
   VPNProviders.setProviders = function(providers) {
-    VPNProviders.getInstance().providers_ = providers;
+    VPNProviders.getInstance().providers = providers;
   };
 
   /**