Created NavigationManager::CopyStateFromAndPrune().

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.
 
 #import "ios/web/navigation/navigation_manager_impl.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 342 matching lines @@
   NavigationItem* item = GetVisibleItem();
   GURL url = item ? item->GetURL() : GURL(url::kAboutBlankURL);
   web::Referrer referrer = item ? item->GetReferrer() : web::Referrer();
 
   WebState::OpenURLParams params(url, referrer,
                                  WindowOpenDisposition::CURRENT_TAB,
                                  ui::PAGE_TRANSITION_RELOAD, NO);
   delegate_->GetWebState()->OpenURL(params);
 }
 
+void NavigationManagerImpl::CopyStateFromAndPrune(
+    const NavigationManager* manager) {
+  DCHECK(manager);
+  CRWSessionController* other_session =
+      static_cast<const NavigationManagerImpl*>(manager)->session_controller_;
+  [session_controller_ copyStateFromSessionControllerAndPrune:other_session];
+}
+
+bool NavigationManagerImpl::CanPruneAllButLastCommittedItem() const {
+  return [session_controller_ canPruneAllButLastCommittedItem];
+}
+
 std::unique_ptr<std::vector<BrowserURLRewriter::URLRewriter>>
 NavigationManagerImpl::GetTransientURLRewriters() {
   return std::move(transient_url_rewriters_);
 }
 
 void NavigationManagerImpl::RemoveTransientURLRewriters() {
   transient_url_rewriters_.reset();
 }
 
 int NavigationManagerImpl::GetIndexForOffset(int offset) const {
@@ skipping 82 matching lines @@
   const ScopedNavigationItemImplList& items = [session_controller_ items];
   while (index >= 0) {
     NavigationItem* item = items[index--].get();
     if (!client->IsAppSpecificURL(item->GetVirtualURL()))
       return item;
   }
   return nullptr;
 }
 
 }  // namespace web