Makes instant run before unload listeners.

chrome/browser/tabs/tab_strip_model.h

 // Copyright (c) 2010 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 CHROME_BROWSER_TABS_TAB_STRIP_MODEL_H_
 #define CHROME_BROWSER_TABS_TAB_STRIP_MODEL_H_
 #pragma once
 
 #include <vector>
 
@@ skipping 177 matching lines @@
   // different NavigationController. This is used through the recently
   // closed tabs list, which needs to replace a tab's current state
   // and history with another set of contents and history.
   //
   // The old NavigationController is deallocated and this object takes
   // ownership of the passed in controller.
   // XXXPINK This API is weird and wrong. Remove it or change it or rename it?
   void ReplaceNavigationControllerAt(int index,
                                      TabContentsWrapper* contents);
 
-  // Replaces the tab contents at |index| with |new_contents|. This deletes the
-  // TabContents currently at |index|.
-  void ReplaceTabContentsAt(int index, TabContentsWrapper* new_contents);
+  // Replaces the tab contents at |index| with |new_contents|. The
+  // TabContentsWrapper that was at |index| is returned and ownership returns
+  // to the caller.
+  TabContentsWrapper* ReplaceTabContentsAt(int index,
+                                           TabContentsWrapper* new_contents);
 
   // Detaches the TabContents at the specified index from this strip. The
   // TabContents is not destroyed, just removed from display. The caller is
   // responsible for doing something with it (e.g. stuffing it into another
   // strip).
   TabContentsWrapper* DetachTabContentsAt(int index);
 
   // Select the TabContents at the specified index. |user_gesture| is true if
   // the user actually clicked on the tab or navigated to it using a keyboard
   // command, false if the tab was selected as a by-product of some other
@@ skipping 349 matching lines @@
   typedef ObserverList<TabStripModelObserver> TabStripModelObservers;
   TabStripModelObservers observers_;
 
   // A scoped container for notification registries.
   NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(TabStripModel);
 };
 
 #endif  // CHROME_BROWSER_TABS_TAB_STRIP_MODEL_H_