ui/login/screen.js : Remove unused methods.

Remove unused:
* declareButton
* declareUserAction

Remove support for HTMLelement attributes:
* <div alias="myDiv"> - remove support for alias=
* <button action="cancel"> - remove support for generating UserAction events
  for buttons having action= attribute.

Bug: 926638
Change-Id: I2c33a7eb375e03deb9bf7f70e176c970de9bf8da
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1519447
Commit-Queue: Alexander Alekseev <alemate@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Cr-Commit-Position: refs/heads/master@{#650566}

ui/login/screen.js

@@ -59,56 +59,6 @@ cr.define('login', function() {
       return this.sendImpl_.apply(this, arguments);
     },
 
-    /**
-     * Creates and returns new button element with given identifier
-     * and on-click event listener, which sends notification about
-     * user action to the C++ side.
-     *
-     * @param {string} id Identifier of a button.
-     * @param {string} opt_action_id Identifier of user action.
-     * @final
-     */
-    declareButton: function(id, opt_action_id) {
-      var button = this.ownerDocument.createElement('button');
-      button.id = id;
-      this.declareUserAction(button,
-                             { action_id: opt_action_id,
-                               event: 'click'
-                             });
-      return button;
-    },
-
-    /**
-      * Adds event listener to an element which sends notification
-      * about event to the C++ side.
-      *
-      * @param {Element} element An DOM element
-      * @param {Object} options A dictionary of optional arguments:
-      *   {string} event: name of event that will be listened,
-      *            default: 'click'.
-      *   {string} action_id: name of an action which will be sent to
-      *                       the C++ side.
-      *   {function} condition: a one-argument function which takes
-      *              event as an argument, notification is sent to the
-      *              C++ side iff condition is true, default: constant
-      *              true function.
-      * @final
-      */
-    declareUserAction: function(element, options) {
-      var self = this;
-      options = options || {};
-
-      var event = options.event || 'click';
-      var action_id = options.action_id || element.id;
-      var condition = options.condition || alwaysTruePredicate;
-
-      element.addEventListener(event, function(e) {
-        if (condition(e))
-          self.sendImpl_(CALLBACK_USER_ACTED, action_id);
-        e.stopPropagation();
-      });
-    },
-
     /**
      * @override
      * @final
@@ -118,34 +68,10 @@ cr.define('login', function() {
     },
 
     /**
-     * Does the following things:
-     *  * Looks for elements having "alias" property and adds them as the
-     *    proprties of the screen with name equal to value of "alias", i.e. HTML
-     *    element <div alias="myDiv"></div> will be stored in this.myDiv.
-     *  * Looks for buttons having "action" properties and adds click handlers
-     *    to them. These handlers send |CALLBACK_USER_ACTED| messages to
-     *    C++ with "action" property's value as payload.
      * @private
      */
     initializeImpl_: function() {
       this.decorate();
-
-      this.querySelectorAllImpl_('[alias]').forEach(function(element) {
-        var alias = element.getAttribute('alias');
-        if (alias in this)
-          throw Error('Alias "' + alias + '" of "' + this.name() + '" screen ' +
-              'shadows or redefines property that is already defined.');
-        this[alias] = element;
-        this[element.getAttribute('alias')] = element;
-      }, this);
-      var self = this;
-      this.querySelectorAllImpl_('button[action]').forEach(function(button) {
-        button.addEventListener('click', function(e) {
-          var action = this.getAttribute('action');
-          self.send(CALLBACK_USER_ACTED, action);
-          e.stopPropagation();
-        });
-      });
     },
 
     /**