[iOS] Refactoring web CRWSessionController user agent code.

ios/web/navigation/crw_session_controller.h

 // Copyright 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.
 
 #ifndef IOS_WEB_NAVIGATION_CRW_SESSION_CONTROLLER_H_
 #define IOS_WEB_NAVIGATION_CRW_SESSION_CONTROLLER_H_
 
 #import <Foundation/Foundation.h>
 #include <vector>
 
@@ skipping 79 matching lines @@
 // CRWSessionController doesn't have public constructors. New
 // CRWSessionControllers are created by deserialization, or via a
 // NavigationManager.
 
 // Sets the corresponding NavigationManager.
 - (void)setNavigationManager:(web::NavigationManagerImpl*)navigationManager;
 // Sets the corresponding BrowserState.
 - (void)setBrowserState:(web::BrowserState*)browserState;
 
 // Add a new item with the given url, referrer, and navigation type, making it
-// the current item. If |url| is the same as the current item's url, this
-// does nothing. |referrer| may be nil if there isn't one. The item starts
-// out as pending, and will be lost unless |-commitPendingItem| is called.
+// the current item. If pending item is the same as current item, this does
+// nothing. |referrer| may be nil if there isn't one. The item starts out as
+// pending, and will be lost unless |-commitPendingItem| is called.

[kkhorimoto, 2017/02/15 23:02:05]

I think the original comment is less ambiguous here since it's talking directly
about the input parameters.

[liaoyuke, 2017/02/16 01:49:04]

But the implementation details is not consistent with the comments, it not only
takes url into consideration, but also page transition types. 

 - (void)addPendingItem:(const GURL&)url
               referrer:(const web::Referrer&)referrer
             transition:(ui::PageTransition)type
      rendererInitiated:(BOOL)rendererInitiated;
 
 // Updates the URL of the yet to be committed pending item. Useful for page
 // redirects. Does nothing if there is no pending item.
 - (void)updatePendingItem:(const GURL&)url;
 
 // Commits the current pending item. No changes are made to the item during
@@ skipping 33 matching lines @@
 // Removes the item at |index| after discarding any noncomitted entries.
 // |index| must not be the index of the last committed item, or a noncomitted
 // item.
 - (void)removeItemAtIndex:(NSInteger)index;
 
 // Determines whether a navigation between |firstEntry| and |secondEntry| is a
 // same-document navigation.  Entries can be passed in any order.
 - (BOOL)isSameDocumentNavigationBetweenItem:(web::NavigationItem*)firstItem
                                     andItem:(web::NavigationItem*)secondItem;
 
-// Set |useDesktopUserAgentForNextPendingItem_| to YES if there is no pending
-// entry, otherwise set |useDesktopUserAgent| in the pending entry.
-- (void)useDesktopUserAgentForNextPendingItem;
-
 // Returns the index of |item| in |items|.
 - (NSInteger)indexOfItem:(const web::NavigationItem*)item;
 
 @end
 
 #endif  // IOS_WEB_NAVIGATION_CRW_SESSION_CONTROLLER_H_