Settings: Fix Clear Browsing Data dialog scrolling to Privacy page

chrome/browser/resources/settings/route.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.
 
 cr.define('settings', function() {
   /**
    * Class for navigable routes. May only be instantiated within this file.
    * @constructor
    * @param {string} path
    * @private
@@ skipping 60 matching lines @@
           return true;
       }
       return false;
     },
 
     /**
      * Returns true if this route is a subpage of a section.
      * @return {boolean}
      */
     isSubpage: function() {
-      return !!this.parent && this.parent.section == this.section;
+      return !!this.parent && !!this.section &&
+          this.parent.section == this.section;
     },
   };
 
   // Abbreviated variable for easier definitions.
   var r = Route;
 
   // Root pages.
   r.BASIC = new Route('/');
   r.ADVANCED = new Route('/advanced');
   r.ABOUT = new Route('/help');
@@ skipping 29 matching lines @@
   r.POINTERS = r.DEVICE.createChild('/pointer-overlay');
   r.KEYBOARD = r.DEVICE.createChild('/keyboard-overlay');
   r.DISPLAY = r.DEVICE.createChild('/display');
   r.NOTES = r.DEVICE.createChild('/note');
 </if>
 
   r.PRIVACY = r.ADVANCED.createSection('/privacy', 'privacy');
   r.CERTIFICATES = r.PRIVACY.createChild('/certificates');
 
   // CLEAR_BROWSER_DATA is the only navigable dialog route. It's the only child
-  // of a section that's not a subpage. Don't add any more routes like these.
+  // of a root page that's not a section. Don't add any more routes like these.
   // If more navigable dialogs are needed, add explicit support in Route.
-  r.CLEAR_BROWSER_DATA = r.PRIVACY.createChild('/clearBrowserData');
-  r.CLEAR_BROWSER_DATA.isSubpage = function() { return false; };
+  r.CLEAR_BROWSER_DATA = r.ADVANCED.createChild('/clearBrowserData');
 
   r.SITE_SETTINGS = r.PRIVACY.createChild('/siteSettings');
   r.SITE_SETTINGS_ALL = r.SITE_SETTINGS.createChild('all');
   r.SITE_SETTINGS_SITE_DETAILS =
       r.SITE_SETTINGS_ALL.createChild('/siteSettings/siteDetails');
 
   r.SITE_SETTINGS_HANDLERS = r.SITE_SETTINGS.createChild('handlers');
 
   // TODO(tommycli): Find a way to refactor these repetitive category routes.
   r.SITE_SETTINGS_AUTOMATIC_DOWNLOADS =
@@ skipping 78 matching lines @@
     },
 
     /** @abstract */
     currentRouteChanged: assertNotReached,
   };
 
   /**
    * Returns the matching canonical route, or null if none matches.
    * @param {string} path
    * @return {?settings.Route}
-   * @private
    */
   var getRouteForPath = function(path) {
     // TODO(tommycli): Use Object.values once Closure compilation supports it.
     var matchingKey = Object.keys(Route).find(function(key) {
       return Route[key].path == path;
     });
 
     return Route[matchingKey] || null;
   };
 
@@ skipping 49 matching lines @@
   /** @return {!URLSearchParams} */
   var getQueryParameters = function() {
     return new URLSearchParams(currentQueryParameters_);  // Defensive copy.
   };
 
   /**
    * Navigates to a canonical route and pushes a new history entry.
    * @param {!settings.Route} route
    * @param {URLSearchParams=} opt_dynamicParameters Navigations to the same
    *     search parameters in a different order will still push to history.
-   * @private
    */
   var navigateTo = function(route, opt_dynamicParameters) {
     var params = opt_dynamicParameters || new URLSearchParams();
 
     var url = route.path;
     if (opt_dynamicParameters) {
       var queryString = opt_dynamicParameters.toString();
       if (queryString)
         url += '?' + queryString;
     }
 
     // History serializes the state, so we don't push the actual route object.
     window.history.pushState(currentRoute_.path, '', url);
     setCurrentRoute(route, params);
   };
 
+  /**
+   * Navigates to the previous route, but will never exit Settings. If there is
+   * no previous route in the history, navigates to the immediate parent.
+   */
+  var navigateToPreviousRoute = function() {
+    var previousRoute =
+        window.history.state &&
+        assert(getRouteForPath(/** @type {string} */ (window.history.state)));
+
+    if (previousRoute)
+      window.history.back();
+    else
+      navigateTo(settings.getCurrentRoute().parent || Route.BASIC);
+  };
+
   window.addEventListener('popstate', function(event) {
     // On pop state, do not push the state onto the window.history again.
     setCurrentRoute(getRouteForPath(window.location.pathname) || Route.BASIC,
                     new URLSearchParams(window.location.search));
   });
 
   return {
     Route: Route,
     RouteObserverBehavior: RouteObserverBehavior,
     getRouteForPath: getRouteForPath,
     initializeRouteFromUrl: initializeRouteFromUrl,
     getCurrentRoute: getCurrentRoute,
     getQueryParameters: getQueryParameters,
     navigateTo: navigateTo,
+    navigateToPreviousRoute: navigateToPreviousRoute,
   };
 });