Handle should_replace_current_entry in prerender.

content/public/browser/navigation_controller.h

 // Copyright (c) 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 CONTENT_PUBLIC_BROWSER_NAVIGATION_CONTROLLER_H_
 #define CONTENT_PUBLIC_BROWSER_NAVIGATION_CONTROLLER_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 390 matching lines @@
   // one should be empty (just created).
   virtual void CopyStateFrom(const NavigationController& source) = 0;
 
   // A variant of CopyStateFrom. Removes all entries from this except the last
   // committed entry, and inserts all entries from |source| before and including
   // its last committed entry. For example:
   // source: A B *C* D
   // this:   E F *G*
   // result: A B C *G*
   // If there is a pending entry after *G* in |this|, it is also preserved.
+  // If |replace_entry| is true, the current entry in |source| is replaced. So
+  // the result above would be A B *G*.
   // This ignores any pending or transient entries in |source|.  Callers must
   // ensure that |CanPruneAllButLastCommitted| returns true before calling this,
   // or it will crash.
-  virtual void CopyStateFromAndPrune(NavigationController* source) = 0;
+  virtual void CopyStateFromAndPrune(NavigationController* source,
+                                     bool replace_entry) = 0;
 
   // Returns whether it is safe to call PruneAllButLastCommitted or
   // CopyStateFromAndPrune.  There must be a last committed entry, no transient
   // entry, and if there is a pending entry, it must be new and not an existing
   // entry.
   //
   // If there were no last committed entry, the pending entry might not commit,
   // leaving us with a blank page.  This is unsafe when used with
   // |CopyStateFromAndPrune|, which would show an existing entry above the blank
   // page.
@@ skipping 18 matching lines @@
 
  private:
   // This interface should only be implemented inside content.
   friend class NavigationControllerImpl;
   NavigationController() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_NAVIGATION_CONTROLLER_H_