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

chrome/browser/history/history_backend.cc

 // 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.
 
 #include "chrome/browser/history/history_backend.h"
 
 #include <list>
 #include <map>
 #include <set>
 #include <vector>
 
+#include "base/callback.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/file_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "base/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/string_util.h"
 #include "base/time.h"
 #include "chrome/browser/autocomplete/history_url_provider.h"
@@ skipping 180 matching lines @@
 HistoryBackend::HistoryBackend(const FilePath& history_dir,
                                int id,
                                Delegate* delegate,
                                BookmarkService* bookmark_service)
     : delegate_(delegate),
       id_(id),
       history_dir_(history_dir),
       ALLOW_THIS_IN_INITIALIZER_LIST(expirer_(this, bookmark_service)),
       recent_redirects_(kMaxRedirectCount),
       backend_destroy_message_loop_(NULL),
-      backend_destroy_task_(NULL),
       segment_queried_(false),
       bookmark_service_(bookmark_service) {
 }
 
 HistoryBackend::~HistoryBackend() {
   DCHECK(!scheduled_commit_) << "Deleting without cleanup";
   ReleaseDBTasks();
 
   // First close the databases before optionally running the "destroy" task.
   if (db_.get()) {
     // Commit the long-running transaction.
     db_->CommitTransaction();
     db_.reset();
   }
   if (thumbnail_db_.get()) {
     thumbnail_db_->CommitTransaction();
     thumbnail_db_.reset();
   }
   if (archived_db_.get()) {
     archived_db_->CommitTransaction();
     archived_db_.reset();
   }
   if (text_database_.get()) {
     text_database_->CommitTransaction();
     text_database_.reset();
   }
 
-  if (backend_destroy_task_) {
+  if (!backend_destroy_task_.is_null()) {
     // Notify an interested party (typically a unit test) that we're done.
     DCHECK(backend_destroy_message_loop_);
     backend_destroy_message_loop_->PostTask(FROM_HERE, backend_destroy_task_);
   }
 }
 
 void HistoryBackend::Init(const std::string& languages, bool force_fail) {
   if (!force_fail)
     InitImpl(languages);
   delegate_->DBLoaded(id_);
 }
 
 void HistoryBackend::SetOnBackendDestroyTask(MessageLoop* message_loop,
-                                             Task* task) {
-  if (backend_destroy_task_) {
+                                             const base::Closure& task) {
+  if (!backend_destroy_task_.is_null())
     DLOG(WARNING) << "Setting more than one destroy task, overriding";
-    delete backend_destroy_task_;
-  }
   backend_destroy_message_loop_ = message_loop;
   backend_destroy_task_ = task;
 }
 
 void HistoryBackend::Closing() {
   // Any scheduled commit will have a reference to us, we must make it
   // release that reference before we can be destroyed.
   CancelScheduledCommit();
 
   // Release our reference to the delegate, this reference will be keeping the
@@ skipping 2047 matching lines @@
         break;
       }
     }
   }
   UMA_HISTOGRAM_TIMES("History.GetFavIconFromDB",  // historical name
                       TimeTicks::Now() - beginning_time);
   return success;
 }
 
 }  // namespace history