uber: use the URL to resolve the subpage in popstate.

chrome/browser/resources/uber/uber.js

 // Copyright (c) 2012 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('uber', function() {
   /**
    * Options for how web history should be handled.
    */
   var HISTORY_STATE_OPTION = {
     PUSH: 1,    // Push a new history state.
@@ skipping 82 matching lines @@
     if (!params.id)
       params.id = getDefaultIframe().id;
 
     return params;
   }
 
   /**
    * Handler for window.onpopstate.
    * @param {Event} e The history event.
    */
   function onPopHistoryState(e) {

[Dan Beam, 2014/05/29 20:42:10]

what happens in the case of !e.state?  should we probably still have an

  if (!e.state)
    return;

here?

[Dan Beam, 2014/05/29 20:45:52]

nevermind, I see what's happening here (and in uber_utils.js), if this is
undefined it's just ignored (essentially) but the popstate still gets forwarded
to replaceState in the outer frame.

-    if (e.state && e.state.pageId) {
-      var params = resolvePageInfo();
-      assert(params.id === e.state.pageId);
+    // Use the URL to determine which page to route to.
+    var params = resolvePageInfo();
 
-      // If the page isn't the current page, load it fresh. Even if the page is
-      // already loaded, it may have state not reflected in the URL, such as the
-      // history page's "Remove selected items" overlay. http://crbug.com/377386
-      if (getRequiredElement(params.id) !== getSelectedIframe())
-        showPage(params.id, HISTORY_STATE_OPTION.NONE, params.path);
+    // If the page isn't the current page, load it fresh. Even if the page is
+    // already loaded, it may have state not reflected in the URL, such as the
+    // history page's "Remove selected items" overlay. http://crbug.com/377386
+    if (getRequiredElement(params.id) !== getSelectedIframe())
+      showPage(params.id, HISTORY_STATE_OPTION.NONE, params.path);
 
-      // Either way, send the state down to it.
-      //
-      // Note: This assumes that the state and path parameters for every page
-      // under this origin are compatible. All of the downstream pages which
-      // navigate use pushState and replaceState.
-      invokeMethodOnPage(e.state.pageId, 'popState',
-                         {state: e.state.pageState, path: params.path});
-    }
+    // Either way, send the state down to it.
+    //
+    // Note: This assumes that the state and path parameters for every page
+    // under this origin are compatible. All of the downstream pages which
+    // navigate use pushState and replaceState.
+    invokeMethodOnPage(params.id, 'popState',
+                       {state: e.state, path: params.path});
   }
 
   /**
    * @return {Object} The default iframe container.
    */
   function getDefaultIframe() {
     return $(loadTimeData.getString('helpHost'));
   }
 
   /**
@@ skipping 100 matching lines @@
 
     var histFunc;
     if (historyOption == HISTORY_STATE_OPTION.PUSH)
       histFunc = window.history.pushState;
     else if (historyOption == HISTORY_STATE_OPTION.REPLACE)
       histFunc = window.history.replaceState;
 
     assert(histFunc, 'invalid historyOption given ' + historyOption);
 
     var pageId = getSelectedIframe().id;
-    var args = [{pageId: pageId, pageState: state},
-                '',
-                '/' + pageId + '/' + (path || '')];
+    var args = [state, '', '/' + pageId + '/' + (path || '')];
     histFunc.apply(window.history, args);
   }
 
   /**
    * Adds or replaces the current history entry based on a navigation from the
    * source iframe.
    * @param {string} origin The origin of the source iframe.
    * @param {Object} state The source iframe's state object.
    * @param {string} path The new "path" (e.g. "/createProfile").
    * @param {boolean} replace Whether to replace the current history entry.
@@ skipping 195 matching lines @@
   }
 
   return {
     onLoad: onLoad,
     onPopHistoryState: onPopHistoryState
   };
 });
 
 window.addEventListener('popstate', uber.onPopHistoryState);
 document.addEventListener('DOMContentLoaded', uber.onLoad);