InstantExtended: remove dead code related to the non-cacheable NTP.

chrome/browser/ui/search/instant_unload_handler.h

-// Copyright 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 CHROME_BROWSER_UI_SEARCH_INSTANT_UNLOAD_HANDLER_H_
-#define CHROME_BROWSER_UI_SEARCH_INSTANT_UNLOAD_HANDLER_H_
-
-#include "base/basictypes.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/scoped_vector.h"
-
-class Browser;
-
-namespace content {
-class WebContents;
-}
-
-// InstantUnloadHandler ensures that it runs the BeforeUnload/Unload Handlers
-// (BUH) of a page if the page is replaced by an Instant overlay.
-//
-// Why is this needed? Say the user is looking at a page P. They then try to
-// navigate to another page Q. Consider what happens with and without Instant:
-//
-// Without Instant: Before the navigation is committed, P's BUH are run. If P's
-// BUH return a string (instead of the default null), the user is prompted to
-// "Stay or Leave?". If the user clicks "Stay", the navigation is cancelled,
-// and the user remains on P.
-//
-// With Instant: The navigation to Q has already happened, since Q is being
-// shown as a preview (overlay). When the user "commits" the overlay, it's too
-// late to cancel Q based on P's BUH. So, Instant just replaces P with Q and
-// passes P to InstantUnloadHandler::RunUnloadListenersOrDestroy(). This class
-// runs P's BUH in the background. If the "Stay or Leave?" dialog needs to be
-// shown, it adds P back onto the tabstrip, next to Q. Otherwise, P is deleted.
-class InstantUnloadHandler {
- public:
-  explicit InstantUnloadHandler(Browser* browser);
-  ~InstantUnloadHandler();
-
-  // See class description for details on what this does.
-  void RunUnloadListenersOrDestroy(scoped_ptr<content::WebContents> contents,
-                                   int index);
-
- private:
-  class WebContentsDelegateImpl;
-
-  // Invoked if the tab is to be shown, at |index| on the tab strip. This
-  // happens if the beforeunload listener returns a string.
-  void Activate(WebContentsDelegateImpl* delegate,
-                scoped_ptr<content::WebContents> contents,
-                int index);
-
-  // Destroys the old tab. This is invoked if script tries to close the page.
-  void Destroy(WebContentsDelegateImpl* delegate);
-
-  // TODO(sky): Browser really needs to wait to close until there are no more
-  // tabs managed by InstantUnloadHandler.
-  Browser* const browser_;
-
-  ScopedVector<WebContentsDelegateImpl> delegates_;
-
-  DISALLOW_COPY_AND_ASSIGN(InstantUnloadHandler);
-};
-
-#endif  // CHROME_BROWSER_UI_SEARCH_INSTANT_UNLOAD_HANDLER_H_