Replaced NavigationContext::IsErrorPage with NavigationContext::GetError

ios/web/public/web_state/web_state_observer.h

 // 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.
 
 #ifndef IOS_WEB_PUBLIC_WEB_STATE_WEB_STATE_OBSERVER_H_
 #define IOS_WEB_PUBLIC_WEB_STATE_WEB_STATE_OBSERVER_H_
 
 #include <stddef.h>
 
 #include <string>
@@ skipping 50 matching lines @@
   // More than one navigation can be ongoing in the same frame at the same
   // time. Each will get its own NavigationHandle.
   //
   // There is no guarantee that DidFinishNavigation() will be called for any
   // particular navigation before DidStartNavigation is called on the next.
   virtual void DidStartNavigation(NavigationContext* navigation_context) {}
 
   // Called when a navigation finished in the WebState for the main frame. This
   // happens when a navigation is committed, aborted or replaced by a new one.
   // To know if the navigation has resulted in an error page, use
-  // NavigationContext::IsErrorPage().
+  // NavigationContext::GetError().
   //
   // If this is called because the navigation committed, then the document load
   // will still be ongoing in the WebState returned by |navigation_context|.
   // Use the document loads events such as DidStopLoading
   // and related methods to listen for continued events from this
   // WebState.
   //
   // This is also fired by same-document navigations, such as fragment
   // navigations or pushState/replaceState, which will not result in a document
   // change. To filter these out, use NavigationContext::IsSameDocument().
@@ skipping 77 matching lines @@
   void ResetWebState();
 
   WebState* web_state_;
 
   DISALLOW_COPY_AND_ASSIGN(WebStateObserver);
 };
 
 }  // namespace web
 
 #endif  // IOS_WEB_PUBLIC_WEB_STATE_WEB_STATE_OBSERVER_H_