Make HistoryDBTask not refcounted, and ensure it's destroyed on its origin thread.

chrome/browser/history/delete_directive_handler.cc

 // Copyright (c) 2013 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/delete_directive_handler.h"
 
 #include "base/json/json_writer.h"
 #include "base/rand_util.h"
 #include "base/time/time.h"
 #include "base/values.h"
@@ skipping 281 matching lines @@
 
 void DeleteDirectiveHandler::Start(
     HistoryService* history_service,
     const syncer::SyncDataList& initial_sync_data,
     scoped_ptr<syncer::SyncChangeProcessor> sync_processor) {
   DCHECK(thread_checker_.CalledOnValidThread());
   sync_processor_ = sync_processor.Pass();
   if (!initial_sync_data.empty()) {
     // Drop processed delete directives during startup.
     history_service->ScheduleDBTask(
-        new DeleteDirectiveTask(weak_ptr_factory_.GetWeakPtr(),
-                                initial_sync_data,
-                                DROP_AFTER_PROCESSING),
+        scoped_ptr<history::HistoryDBTask>(
+            new DeleteDirectiveTask(weak_ptr_factory_.GetWeakPtr(),
+                                    initial_sync_data,
+                                    DROP_AFTER_PROCESSING)),
         &internal_tracker_);
   }
 }
 
 void DeleteDirectiveHandler::Stop() {
   DCHECK(thread_checker_.CalledOnValidThread());
   sync_processor_.reset();
 }
 
 bool DeleteDirectiveHandler::CreateDeleteDirectives(
@@ skipping 87 matching lines @@
         NOTREACHED();
         break;
     }
   }
 
   if (!delete_directives.empty()) {
     // Don't drop real-time delete directive so that sync engine can detect
     // redelivered delete directives to avoid processing them again and again
     // in one chrome session.
     history_service->ScheduleDBTask(
-        new DeleteDirectiveTask(weak_ptr_factory_.GetWeakPtr(),
-                                delete_directives,
-                                KEEP_AFTER_PROCESSING),
+        scoped_ptr<history::HistoryDBTask>(
+            new DeleteDirectiveTask(weak_ptr_factory_.GetWeakPtr(),
+                                    delete_directives,
+                                    KEEP_AFTER_PROCESSING)),
         &internal_tracker_);
   }
   return syncer::SyncError();
 }
 
 void DeleteDirectiveHandler::FinishProcessing(
     PostProcessingAction post_processing_action,
     const syncer::SyncDataList& delete_directives) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   // If specified, drop processed delete directive in sync model because they
   // only need to be applied once.
   if (sync_processor_.get() &&
       post_processing_action == DROP_AFTER_PROCESSING) {
     syncer::SyncChangeList change_list;
     for (size_t i = 0; i < delete_directives.size(); ++i) {
       change_list.push_back(
           syncer::SyncChange(FROM_HERE, syncer::SyncChange::ACTION_DELETE,
                              delete_directives[i]));
     }
     sync_processor_->ProcessSyncChanges(FROM_HERE, change_list);
   }
 }
 
 }  // namespace history