Remove code duplication in PageManager

ui/webui/resources/js/cr/ui/page_manager/page_manager.js

 // Copyright 2014 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.
 
 cr.define('cr.ui.pageManager', function() {
   /** @const */ var FocusOutlineManager = cr.ui.FocusOutlineManager;
 
   /**
    * PageManager contains a list of root Page and overlay Page objects and
    * handles "navigation" by showing and hiding these pages and overlays. On
@@ skipping 163 matching lines @@
 
       pageName = targetPage.name.toLowerCase();
       var targetPageWasVisible = targetPage.visible;
 
       // Determine if the root page is 'sticky', meaning that it
       // shouldn't change when showing an overlay. This can happen for special
       // pages like Search.
       var isRootPageLocked =
           rootPage && rootPage.sticky && targetPage.parentPage;
 
-      var allPageNames = Array.prototype.concat.call(
-          Object.keys(this.registeredPages),
-          Object.keys(this.registeredOverlayPages));
-
       // Notify pages if they will be hidden.
-      // TODO(michaelpg): Resolve code duplication.
-      for (var i = 0; i < allPageNames.length; ++i) {
-        var name = allPageNames[i];
-        var page = this.registeredPages[name] ||
-                   this.registeredOverlayPages[name];
-        if (!page.parentPage && isRootPageLocked)
-          continue;
-        if (page.willHidePage && name != pageName &&
+      this.forEachPage_(!isRootPageLocked, function(page) {
+        if (page.willHidePage && page.name != pageName &&
             !this.isAncestorOfPage(page, targetPage)) {
           page.willHidePage();
         }
-      }
+      });
 
       // Update visibilities to show only the hierarchy of the target page.
-      for (var i = 0; i < allPageNames.length; ++i) {
-        var name = allPageNames[i];
-        var page = this.registeredPages[name] ||
-                   this.registeredOverlayPages[name];
-        if (!page.parentPage && isRootPageLocked)
-          continue;
-        page.visible = name == pageName ||
+      this.forEachPage_(!isRootPageLocked, function(page) {
+        page.visible = page.name == pageName ||
                        this.isAncestorOfPage(page, targetPage);
-      }
+      });
 
       // Update the history and current location.
       if (opt_updateHistory)
         this.updateHistoryState_(!!opt_propertyBag.replaceState);
 
       // Update focus if any other control was focused on the previous page,
       // or the previous page is not known.
       if (document.activeElement != document.body &&
           (!rootPage || rootPage.pageDiv.contains(document.activeElement))) {
         targetPage.focus();
       }
 
       // Notify pages if they were shown.
-      for (var i = 0; i < allPageNames.length; ++i) {
-        var name = allPageNames[i];
-        var page = this.registeredPages[name] ||
-                   this.registeredOverlayPages[name];
-        if (!page.parentPage && isRootPageLocked)
-          continue;
+      this.forEachPage_(!isRootPageLocked, function(page) {
         if (!targetPageWasVisible && page.didShowPage &&
-            (name == pageName || this.isAncestorOfPage(page, targetPage))) {
+            (page.name == pageName ||
+             this.isAncestorOfPage(page, targetPage))) {
           page.didShowPage();
         }
-      }
+      });
 
       // Update the document title. Do this after didShowPage was called, in
       // case a page decides to change its title.
       this.updateTitle_();
     },
 
     /**
      * Returns the name of the page from the current path.
      * @return {string} Name of the page specified by the current path.
      */
@@ skipping 461 matching lines @@
      * @private
      */
     updateFrozenElementHorizontalPosition_: function(e) {
       if (isRTL()) {
         e.style.right = this.horizontalOffset + 'px';
       } else {
         var scrollLeft = scrollLeftForDocument(document);
         e.style.left = this.horizontalOffset - scrollLeft + 'px';
       }
     },
+
+    /**
+     * Calls the given callback with each registered page.
+     * @param {boolean} includeRootPages Whether the callback should be called
+     *     for the root pages.
+     * @param {function(cr.ui.pageManager.Page)} callback The callback.
+     * @private
+     */
+    forEachPage_: function(includeRootPages, callback) {
+      var pageNames = Object.keys(this.registeredOverlayPages);
+      if (includeRootPages)
+        pageNames = Object.keys(this.registeredPages).concat(pageNames);
+
+      pageNames.forEach(function(name) {
+        callback.call(this, this.registeredOverlayPages[name] ||
+                            this.registeredPages[name]);
+      }, this);
+    },
   };
 
   /**
    * An observer of PageManager.
    * @interface
    */
   PageManager.Observer = function() {}
 
   PageManager.Observer.prototype = {
     /**
@@ skipping 14 matching lines @@
      * @param {boolean} replace If true, allow no history events to be created.
      */
     updateHistory: function(path, replace) {},
   };
 
   // Export
   return {
     PageManager: PageManager
   };
 });