Remove CRWSessionEntry from NavigationManagerImpl.

ios/web/public/navigation_manager.h

Index: ios/web/public/navigation_manager.h
diff --git a/ios/web/public/navigation_manager.h b/ios/web/public/navigation_manager.h
index bec6c696e9d91976aa8beacb7be49e8835d33c52..3cd75e3613e268ed9c5396ae3eb51473a30cde7d 100644
--- a/ios/web/public/navigation_manager.h
+++ b/ios/web/public/navigation_manager.h
@@ -112,25 +112,30 @@ class NavigationManager {
 
   // 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 from which web would go back/forward or reload.
+  // TODO(crbug.com/533848): Update to return size_t.
   virtual int GetCurrentItemIndex() 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;
 
   // Removes the item at the specified |index|.  If the index is the last
   // committed index or the pending item, this does nothing and returns false.
   // Otherwise this call discards any transient or pending entries.
+  // TODO(crbug.com/533848): Update to use size_t.
   virtual bool RemoveItemAtIndex(int index) = 0;
 
   // Navigation relative to the current item.
@@ -141,6 +146,7 @@ class NavigationManager {
   virtual void GoForward() = 0;
 
   // Navigates to the specified absolute index.
+  // TODO(crbug.com/533848): Update to use size_t.
   virtual void GoToIndex(int index) = 0;
 
   // Reloads the current item. If |check_for_repost| is true and the current