Remove TabModel -replaceWebState: method.

ios/chrome/browser/tabs/tab_private.h

 // Copyright 2015 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_CHROME_BROWSER_TABS_TAB_PRIVATE_H_
 #define IOS_CHROME_BROWSER_TABS_TAB_PRIVATE_H_
 
 #include "ios/net/request_tracker.h"
 
 namespace web {
 class WebStateImpl;
 }
 
 // Exposed private methods for testing purpose.
 @interface Tab ()
 
 - (OpenInController*)openInController;
 - (void)closeThisTab;
 - (CRWSessionEntry*)currentSessionEntry;
 - (void)setShouldObserveInfoBarManager:(BOOL)shouldObserveInfoBarManager;
 - (void)setShouldObserveFaviconChanges:(BOOL)shouldObserveFaviconChanges;
 
 @end
 
 @interface Tab (TestingSupport)
 
-// Replaces the existing web state. This method should be called once
-// right after init and before any call to |view|.
-// TODO(crbug.com/620465): change to std::unique_ptr<web::WebState> once
-// Tab no longer uses private //ios/web APIs.
-- (void)replaceWebState:(std::unique_ptr<web::WebStateImpl>)webState;
-
 // Replaces the existing |externalAppLauncher_|.
 - (void)replaceExternalAppLauncher:(id)externalAppLauncher;
 
 - (TabModel*)parentTabModel;
 
 - (FormInputAccessoryViewController*)inputAccessoryViewController;
 
 @end
 
 #endif  // IOS_CHROME_BROWSER_TABS_TAB_PRIVATE_H_