Eliminated the last few uses of MessageLoop::QuitTask in chrome/

chrome/browser/history/history.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_HISTORY_HISTORY_H_
 #define CHROME_BROWSER_HISTORY_HISTORY_H_
 #pragma once
 
 #include <set>
 #include <vector>
@@ skipping 511 matching lines @@
 
   // Designed for unit tests, this passes the given task on to the history
   // backend to be called once the history backend has terminated. This allows
   // callers to know when the history thread is complete and the database files
   // can be deleted and the next test run. Otherwise, the history thread may
   // still be running, causing problems in subsequent tests.
   //
   // There can be only one closing task, so this will override any previously
   // set task. We will take ownership of the pointer and delete it when done.
   // The task will be run on the calling thread (this function is threadsafe).
-  void SetOnBackendDestroyTask(Task* task);
+  void SetOnBackendDestroyTask(const base::Closure& task);
 
   // Used for unit testing and potentially importing to get known information
   // into the database. This assumes the URL doesn't exist in the database
   //
   // Calling this function many times may be slow because each call will
   // dispatch to the history thread and will be a separate database
   // transaction. If this functionality is needed for importing many URLs,
   // callers should use AddPagesWithDetails() instead.
   //
   // Note that this routine (and AddPageWithDetails()) always adds a single
@@ skipping 316 matching lines @@
   BookmarkService* bookmark_service_;
   bool no_db_;
 
   // True if needs top site migration.
   bool needs_top_sites_migration_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryService);
 };
 
 #endif  // CHROME_BROWSER_HISTORY_HISTORY_H_