Fix another source of flakiness in ErrorPageTest

chrome/browser/automation/automation_provider.h

 // Copyright (c) 2006-2008 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.
 
 // This implements a browser-side endpoint for UI automation activity.
 // The client-side endpoint is implemented by AutomationProxy.
 // The entire lifetime of this object should be contained within that of
 // the BrowserProcess, and in particular the NotificationService that's
 // hung off of it.
 
@@ skipping 448 matching lines @@
   void Paste(int tab_handle);
 
   void ReloadAsync(int tab_handle);
   void StopAsync(int tab_handle);
 
   void WaitForBrowserWindowCountToBecome(int target_count,
                                          IPC::Message* reply_message);
 
   void WaitForAppModalDialogToBeShown(IPC::Message* reply_message);
 
+  void GoBackBlockUntilNavigationsComplete(int handle,
+                                           int number_of_navigations,
+                                           IPC::Message* reply_message);
+
+  void GoForwardBlockUntilNavigationsComplete(int handle,
+                                              int number_of_navigations,
+                                              IPC::Message* reply_message);
+
   // Convert a tab handle into a TabContents. If |tab| is non-NULL a pointer
   // to the tab is also returned. Returns NULL in case of failure or if the tab
   // is not of the TabContents type.
   TabContents* GetTabContentsForHandle(int handle, NavigationController** tab);
 
   ExternalTabContainer* GetExternalTabForHandle(int handle);
 
   // Callback for history redirect queries.
   virtual void OnRedirectQueryComplete(
       HistoryService::Handle request_handle,
@@ skipping 74 matching lines @@
   virtual void Observe(NotificationType type,
                        const NotificationSource& source,
                        const NotificationDetails& details);
 
   void OnRemoveProvider();  // Called via PostTask
 
   NotificationRegistrar registrar_;
 };
 
 #endif  // CHROME_BROWSER_AUTOMATION_AUTOMATION_PROVIDER_H_