Add SwappedOut to TabContentsDelegate to allow us to correctly delete TabContents.

content/browser/tab_contents/tab_contents_delegate.h

 // Copyright (c) 2011 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_BROWSER_TAB_CONTENTS_TAB_CONTENTS_DELEGATE_H_
 #define CONTENT_BROWSER_TAB_CONTENTS_TAB_CONTENTS_DELEGATE_H_
 #pragma once
 
 #include <set>
 #include <string>
@@ skipping 101 matching lines @@
   // |progress| is a value between 0.0 (nothing loaded) to 1.0 (page fully
   // loaded).
   // Note that to receive this notification, you must have called
   // SetReportLoadProgressEnabled(true) in the render view.
   virtual void LoadProgressChanged(double progress);
 
   // Request the delegate to close this tab contents, and do whatever cleanup
   // it needs to do.
   virtual void CloseContents(TabContents* source);
 
+  // Informs the delegate that the underlying RenderViewHost has been swapped
+  // out so it can perform any cleanup necessary.
+  virtual void SwappedOut(TabContents* source);
+
   // Request the delegate to move this tab contents to the specified position
   // in screen coordinates.
   virtual void MoveContents(TabContents* source, const gfx::Rect& pos);
 
   // Causes the delegate to detach |source| and clean up any internal data
   // pointing to it.  After this call ownership of |source| passes to the
   // caller, and it is safe to call "source->set_delegate(someone_else);".
   virtual void DetachContents(TabContents* source);
 
   // Called to determine if the TabContents is contained in a popup window
@@ skipping 244 matching lines @@
   void Attach(TabContents* source);
 
   // Called when |this| is no longer the TabContentsDelegate for |source|.
   void Detach(TabContents* source);
 
   // The TabContents that this is currently a delegate for.
   std::set<TabContents*> attached_contents_;
 };
 
 #endif  // CONTENT_BROWSER_TAB_CONTENTS_TAB_CONTENTS_DELEGATE_H_