[MD settings] lighter weight initializer for protocol handler enabled messages

chrome/browser/resources/settings/site_settings/site_settings_prefs_browser_proxy.js

 // Copyright 2016 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 helper object used from the "Site Settings" section to
  * interact with the content settings prefs.
  */
 
 /**
@@ skipping 190 matching lines @@
     removeCookie: function(path) {},
 
     /**
      * Removes all cookies.
      * @return {!Promise<!CookieList>} Returns the up to date
      *     cookie list once deletion is complete (empty list).
      */
     removeAllCookies: function() {},
 
     /**
-     * Initializes the protocol handler list. List is returned through JS calls
-     * to setHandlersEnabled, setProtocolHandlers & setIgnoredProtocolHandlers.
+     * observes _all_ of the the protocol handler state, which includes a list
+     * that is returned through JS calls to 'setProtocolHandlers' along with
+     * other state sent with the messages 'setIgnoredProtocolHandler' and
+     * 'setHandlersEnabled'.
      */
-    initializeProtocolHandlerList: function() {},
+    observeProtocolHandlers: function() {},
+
+    /**
+     * Observes one aspect of the protocol handler so that updates to the
+     * enabled/disabled state are sent. A 'setHandlersEnabled' will be sent
+     * from C++ immediately after receiving this observe request and updates
+     * may follow via additional 'setHandlersEnabled' messages.
+     *
+     * If |observeProtocolHandlers| is called, there's no need to call this
+     * observe as well.
+     */
+    observeProtocolHandlersEnabledState: function() {},
 
     /**
      * Enables or disables the ability for sites to ask to become the default
      * protocol handlers.
      * @param {boolean} enabled Whether sites can ask to become default.
      */
     setProtocolHandlerDefault: function(enabled) {},
 
     /**
      * Sets a certain url as default for a given protocol handler.
@@ skipping 122 matching lines @@
     /** @override */
     removeCookie: function(path) {
       chrome.send('removeCookie', [path]);
     },
 
     /** @override */
     removeAllCookies: function() {
       return cr.sendWithPromise('removeAllCookies');
     },
 
-    initializeProtocolHandlerList: function() {
-      chrome.send('initializeProtocolHandlerList');
+    /** @override */
+    observeProtocolHandlers: function() {
+      chrome.send('observeProtocolHandlers');
     },
 
     /** @override */
+    observeProtocolHandlersEnabledState: function() {
+      chrome.send('observeProtocolHandlersEnabledState');
+    },
+
+    /** @override */
     setProtocolHandlerDefault: function(enabled) {
       chrome.send('setHandlersEnabled', [enabled]);
     },
 
     /** @override */
     setProtocolDefault: function(protocol, url) {
       chrome.send('setDefault', [[protocol, url]]);
     },
 
     /** @override */
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     removeZoomLevel: function(host) {
       chrome.send('removeZoomLevel', [host]);
     },
   };
 
   return {
     SiteSettingsPrefsBrowserProxy: SiteSettingsPrefsBrowserProxy,
     SiteSettingsPrefsBrowserProxyImpl: SiteSettingsPrefsBrowserProxyImpl,
   };
 });