[Android] Upstream remaining changes to NTP UI code.

chrome/browser/ui/webui/ntp/recently_closed_tabs_handler.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 CHROME_BROWSER_UI_WEBUI_NTP_RECENTLY_CLOSED_TABS_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_NTP_RECENTLY_CLOSED_TABS_HANDLER_H_
 
 #include "base/values.h"
 #include "chrome/browser/sessions/tab_restore_service.h"
 #include "chrome/browser/sessions/tab_restore_service_observer.h"
@@ skipping 11 matching lines @@
   virtual void RegisterMessages() OVERRIDE;
 
   // Callback for the "reopenTab" message. Rewrites the history of the
   // currently displayed tab to be the one in TabRestoreService with a
   // history of a session passed in through the content pointer.
   void HandleReopenTab(const ListValue* args);
 
   // Callback for the "getRecentlyClosedTabs" message.
   void HandleGetRecentlyClosedTabs(const ListValue* args);
 
+  // Callback for the "clearRecentlyClosed" message.
+  void HandleClearRecentlyClosed(const ListValue* args);
+
   // Observer callback for TabRestoreServiceObserver. Sends data on
   // recently closed tabs to the javascript side of this page to
   // display to the user.
   virtual void TabRestoreServiceChanged(TabRestoreService* service) OVERRIDE;
 
   // Observer callback to notice when our associated TabRestoreService
   // is destroyed.
   virtual void TabRestoreServiceDestroyed(TabRestoreService* service) OVERRIDE;
 
   // Converts a list of TabRestoreService entries to the JSON format required
   // by the NTP and adds them to the given list value.
   static void CreateRecentlyClosedValues(
       const TabRestoreService::Entries& entries,
       base::ListValue* entry_list_value);
 
  private:
+  // Construct and initialize tab_restore_service_ if it's NULL.
+  // tab_restore_service_ may still be NULL, however, in incognito mode.
+  void EnsureTabRestoreService();
+
   // TabRestoreService that we are observing.
   TabRestoreService* tab_restore_service_;
 
   DISALLOW_COPY_AND_ASSIGN(RecentlyClosedTabsHandler);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_NTP_RECENTLY_CLOSED_TABS_HANDLER_H_