[SyncFS] Clear sync task runners on shutdown of SyncFileSystemService

chrome/browser/sync_file_system/sync_file_system_service.cc

 // Copyright (c) 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.
 
 #include "chrome/browser/sync_file_system/sync_file_system_service.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/format_macros.h"
@@ skipping 233 matching lines @@
   base::WeakPtrFactory<RemoteSyncRunner> factory_;
   DISALLOW_COPY_AND_ASSIGN(RemoteSyncRunner);
 };
 
 //-----------------------------------------------------------------------------
 // SyncFileSystemService
 
 void SyncFileSystemService::Shutdown() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
+  local_sync_runners_.clear();
+  remote_sync_runners_.clear();
+
   local_service_->Shutdown();
   local_service_.reset();
 
   remote_service_.reset();
   v2_remote_service_.reset();
 
   ProfileSyncServiceBase* profile_sync_service =
       ProfileSyncServiceFactory::GetForProfile(profile_);
   if (profile_sync_service)
     profile_sync_service->RemoveObserver(this);
@@ skipping 485 matching lines @@
     v2_remote_service_->AddServiceObserver(v2_remote_syncer.get());
     v2_remote_service_->AddFileStatusObserver(this);
     v2_remote_service_->SetRemoteChangeProcessor(local_service_.get());
     v2_remote_service_->SetSyncEnabled(sync_enabled_);
     remote_sync_runners_.push_back(v2_remote_syncer.release());
   }
   return v2_remote_service_.get();
 }
 
 }  // namespace sync_file_system