Convert //ios from scoped_ptr to std::unique_ptr.

ios/web/navigation/navigation_manager_impl.mm

 // Copyright 2013 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.
 
 #include "ios/web/navigation/navigation_manager_impl.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 288 matching lines @@
   }
 }
 
 void NavigationManagerImpl::Reload(bool check_for_reposts) {
   NavigationItem* item = GetVisibleItem();
   WebState::OpenURLParams params(item->GetURL(), item->GetReferrer(),
                                  CURRENT_TAB, ui::PAGE_TRANSITION_RELOAD, NO);
   delegate_->GetWebState()->OpenURL(params);
 }
 
-scoped_ptr<std::vector<BrowserURLRewriter::URLRewriter>>
+std::unique_ptr<std::vector<BrowserURLRewriter::URLRewriter>>
 NavigationManagerImpl::GetTransientURLRewriters() {
   return std::move(transient_url_rewriters_);
 }
 
 void NavigationManagerImpl::RemoveTransientURLRewriters() {
   transient_url_rewriters_.reset();
 }
 
 void NavigationManagerImpl::CopyState(
     NavigationManagerImpl* navigation_manager) {
   SetSessionController(
       [[navigation_manager->GetSessionController() copy] autorelease]);
 }
 
 }  // namespace web