Added NavigationManager::GetIndexOfItem().

ios/web/public/navigation_manager.h

 // 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.
 
 #ifndef IOS_WEB_PUBLIC_NAVIGATION_MANAGER_H_
 #define IOS_WEB_PUBLIC_NAVIGATION_MANAGER_H_
 
 #include <stddef.h>
 
 #import "base/mac/scoped_nsobject.h"
@@ skipping 112 matching lines @@
       BrowserURLRewriter::URLRewriter rewriter) = 0;
 
   // Returns the number of items in the NavigationManager, excluding
   // pending and transient entries.
   // TODO(crbug.com/533848): Update to return size_t.
   virtual int GetItemCount() const = 0;
 
   // Returns the committed NavigationItem at |index|.
   virtual NavigationItem* GetItemAtIndex(size_t index) const = 0;
 
+  // Returns the index of |item| in the committed session history.
+  virtual int GetIndexOfItem(const NavigationItem* item) const = 0;
+
   // Returns the index of the last committed item or -1 if the last
   // committed item correspond to a new navigation.
   // TODO(crbug.com/533848): Update to return size_t.
   virtual int GetLastCommittedItemIndex() const = 0;
 
   // Returns the index of the pending item or -1 if the pending item
   // corresponds to a new navigation.
   // TODO(crbug.com/533848): Update to return size_t.
   virtual int GetPendingItemIndex() const = 0;
 
@@ skipping 44 matching lines @@
   // This is true when all the following conditions are met:
   // - There is a last committed NavigationItem.
   // - There is no pending history navigation.
   // - There is no transient NavigationItem.
   virtual bool CanPruneAllButLastCommittedItem() const = 0;
 };
 
 }  // namespace web
 
 #endif  // IOS_WEB_PUBLIC_NAVIGATION_MANAGER_H_