Created NavigationManager::CopyStateFromAndPrune().

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 23 matching lines @@
 @property(nonatomic, readonly, assign) NSInteger previousNavigationIndex;
 // The index of the pending item if it is in |items|, or -1 if |pendingItem|
 // corresponds with a new navigation (created by addPendingItem:).
 @property(nonatomic, readwrite, assign) NSInteger pendingItemIndex;
 // Indicates whether the page was opened by DOM (e.g. with |window.open|
 // JavaScript call or by clicking a link with |_blank| target).
 @property(nonatomic, readonly, getter=isOpenedByDOM) BOOL openedByDOM;
 @property(nonatomic, readonly, strong)
     CRWSessionCertificatePolicyManager* sessionCertificatePolicyManager;
 
+// Whether the CRWSessionController can prune all but the last committed item.
+// This is true when all the following conditions are met:
+// - There is a last committed NavigationItem
+// - There is not currently a pending history navigation
+// - There is no transient NavigationItem.
+@property(nonatomic, readonly) BOOL canPruneAllButLastCommittedItem;
+
 // The ScopedNavigationItemImplList used to store the NavigationItemImpls for
 // this session.
 @property(nonatomic, readonly) const web::ScopedNavigationItemImplList& items;
 // The current NavigationItem.  During a pending navigation, returns the
 // NavigationItem for that navigation.  If a transient NavigationItem exists,
 // this NavigationItem will be returned.
 @property(nonatomic, readonly) web::NavigationItemImpl* currentItem;
 // Returns the NavigationItem whose URL should be displayed to the user.
 @property(nonatomic, readonly) web::NavigationItemImpl* visibleItem;
 // Returns the NavigationItem corresponding to a load for which no data has yet
@@ skipping 58 matching lines @@
                stateObject:(NSString*)stateObject
                 transition:(ui::PageTransition)transition;
 
 // Updates the URL and state object for the current item.
 - (void)updateCurrentItemWithURL:(const GURL&)url
                      stateObject:(NSString*)stateObject;
 
 // Removes the pending and transient NavigationItems.
 - (void)discardNonCommittedItems;
 
-// Inserts history state from |otherController| to the front of |items|.  This
-// function will create copies of |otherController|'s NavigationItems.
-- (void)insertStateFromSessionController:(CRWSessionController*)otherController;
+// Removes all items from this except the last committed item, and inserts
+// copies of all items from |source| at the beginning of the session history.
+//
+// For example:
+// source: A B *C* D
+// this:   E F *G*
+// result: A B C *G*
+//
+// If there is a pending item after *G* in |this|, it is also preserved.
+// This ignores any pending or transient entries in |source|.  No-op if
+// |canPruneAllButLastCommittedItem| is false.
+- (void)copyStateFromSessionControllerAndPrune:(CRWSessionController*)source;
 
 // Sets |currentNavigationIndex_| to the |index| if it's in the entries bounds.
 - (void)goToItemAtIndex:(NSInteger)index;
 
 // 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;
 
 // Returns the index of |item| in |items|.
 - (NSInteger)indexOfItem:(const web::NavigationItem*)item;
 
 // Returns the item at |index| in |items|.
 - (web::NavigationItemImpl*)itemAtIndex:(NSInteger)index;
 
 @end
 
 #endif  // IOS_WEB_NAVIGATION_CRW_SESSION_CONTROLLER_H_