MD Settings: Add remaining buttons to keyboard subpage

chrome/browser/resources/settings/device_page/device_page_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 for testing the Device page. */
 cr.define('settings', function() {
   /** @interface */
   function DevicePageBrowserProxy() {}
 
   DevicePageBrowserProxy.prototype = {
     /**
      * Override to interact with the on-tap/on-keydown event on the Learn More
      * link.
      * @param {!Event} e
      */
     handleLinkEvent: function(e) {},
+
+    /** Initializes the keyboard WebUI handler. */
+    initializeKeyboard: function() {},
+
+    /** Shows the Ash keyboard shortcuts overlay. */
+    showKeyboardShortcutsOverlay: function() {},
   };
 
   /**
    * @constructor
    * @implements {settings.DevicePageBrowserProxy}
    */
   function DevicePageBrowserProxyImpl() {}
   cr.addSingletonGetter(DevicePageBrowserProxyImpl);
 
   DevicePageBrowserProxyImpl.prototype = {
     /** override */
     handleLinkEvent: function(e) {
       // Prevent the link from activating its parent element when tapped or
       // when Enter is pressed.
       if (e.type != 'keydown' || e.keyCode == 13)
         e.stopPropagation();
     },
+
+    /** @override */
+    initializeKeyboard: function() {
+      chrome.send('initializeKeyboardSettings');
+    },
+
+    /** @override */
+    showKeyboardShortcutsOverlay: function() {
+      chrome.send('showKeyboardShortcutsOverlay');
+    },
   };
 
   return {
     DevicePageBrowserProxy: DevicePageBrowserProxy,
     DevicePageBrowserProxyImpl: DevicePageBrowserProxyImpl,
   };
 });