[SyncFS] Construct and destruct sync_worker in worker_task_runner

chrome/browser/sync_file_system/drive_backend/sync_worker.cc

Index: chrome/browser/sync_file_system/drive_backend/sync_worker.cc
diff --git a/chrome/browser/sync_file_system/drive_backend/sync_worker.cc b/chrome/browser/sync_file_system/drive_backend/sync_worker.cc
index c2b7f87f6c4845a891b87221d8f8b1b5d3f5d626..3bd73207b1754eb5a1dd5b18e819628f137a790b 100644
--- a/chrome/browser/sync_file_system/drive_backend/sync_worker.cc
+++ b/chrome/browser/sync_file_system/drive_backend/sync_worker.cc
@@ -85,6 +85,7 @@ void QueryAppStatusOnUIThread(
 
 }  // namespace
 
+// static
 scoped_ptr<SyncWorker> SyncWorker::CreateOnWorker(
     const base::FilePath& base_dir,
     Observer* observer,
@@ -97,7 +98,6 @@ scoped_ptr<SyncWorker> SyncWorker::CreateOnWorker(
                      sync_engine_context.Pass(),
                      env_override));
   sync_worker->AddObserver(observer);
-  sync_worker->Initialize();
 
   return sync_worker.Pass();
 }
@@ -108,7 +108,8 @@ void SyncWorker::Initialize() {
   DCHECK(!task_manager_);
 
   task_manager_.reset(new SyncTaskManager(
-      weak_ptr_factory_.GetWeakPtr(), 0 /* maximum_background_task */));
+      AsWeakPtr(),
+      0 /* maximum_background_task */));
   task_manager_->Initialize(SYNC_STATUS_OK);
 
   PostInitializeTask();
@@ -133,7 +134,6 @@ void SyncWorker::RegisterOrigin(
     return;
   }
 
-  // TODO(peria): Forward |callback| to UI thread.
   task_manager_->ScheduleSyncTask(
       FROM_HERE,
       task.PassAs<SyncTask>(),
@@ -144,11 +144,10 @@ void SyncWorker::RegisterOrigin(
 void SyncWorker::EnableOrigin(
     const GURL& origin,
     const SyncStatusCallback& callback) {
-  // TODO(peria): Forward |callback| to UI thread.
   task_manager_->ScheduleTask(
       FROM_HERE,
       base::Bind(&SyncWorker::DoEnableApp,
-                 weak_ptr_factory_.GetWeakPtr(),
+                 AsWeakPtr(),
                  origin.host()),
       SyncTaskManager::PRIORITY_HIGH,
       callback);
@@ -157,11 +156,10 @@ void SyncWorker::EnableOrigin(
 void SyncWorker::DisableOrigin(
     const GURL& origin,
     const SyncStatusCallback& callback) {
-  // TODO(peria): Forward |callback| to UI thread.
   task_manager_->ScheduleTask(
       FROM_HERE,
       base::Bind(&SyncWorker::DoDisableApp,
-                 weak_ptr_factory_.GetWeakPtr(),
+                 AsWeakPtr(),
                  origin.host()),
       SyncTaskManager::PRIORITY_HIGH,
       callback);
@@ -171,7 +169,6 @@ void SyncWorker::UninstallOrigin(
     const GURL& origin,
     RemoteFileSyncService::UninstallFlag flag,
     const SyncStatusCallback& callback) {
-  // TODO(peria): Forward |callback| to UI thread.
   task_manager_->ScheduleSyncTask(
       FROM_HERE,
       scoped_ptr<SyncTask>(
@@ -188,7 +185,7 @@ void SyncWorker::ProcessRemoteChange(
       scoped_ptr<SyncTask>(syncer),
       SyncTaskManager::PRIORITY_MED,
       base::Bind(&SyncWorker::DidProcessRemoteChange,
-                 weak_ptr_factory_.GetWeakPtr(),
+                 AsWeakPtr(),
                  syncer, callback));
 }
 
@@ -290,7 +287,7 @@ void SyncWorker::ApplyLocalChange(
       scoped_ptr<SyncTask>(syncer),
       SyncTaskManager::PRIORITY_MED,
       base::Bind(&SyncWorker::DidApplyLocalChange,
-                 weak_ptr_factory_.GetWeakPtr(),
+                 AsWeakPtr(),
                  syncer, callback));
 }
 
@@ -397,8 +394,7 @@ SyncWorker::SyncWorker(
           CONFLICT_RESOLUTION_POLICY_LAST_WRITE_WIN),
       network_available_(false),
       extension_service_(extension_service),
-      context_(sync_engine_context.Pass()),
-      weak_ptr_factory_(this) {}
+      context_(sync_engine_context.Pass()) {}
 
 void SyncWorker::DoDisableApp(const std::string& app_id,
                               const SyncStatusCallback& callback) {
@@ -434,7 +430,7 @@ void SyncWorker::PostInitializeTask() {
       scoped_ptr<SyncTask>(initializer),
       SyncTaskManager::PRIORITY_HIGH,
       base::Bind(&SyncWorker::DidInitialize,
-                 weak_ptr_factory_.GetWeakPtr(),
+                 AsWeakPtr(),
                  initializer));
 }
 
@@ -469,7 +465,7 @@ void SyncWorker::UpdateRegisteredApp() {
   AppStatusMap* app_status = new AppStatusMap;
   base::Closure callback =
       base::Bind(&SyncWorker::DidQueryAppStatus,
-                 weak_ptr_factory_.GetWeakPtr(),
+                 AsWeakPtr(),
                  base::Owned(app_status));
 
   context_->GetUITaskRunner()->PostTask(
@@ -583,7 +579,7 @@ void SyncWorker::DidApplyLocalChange(LocalToRemoteSyncer* syncer,
         scoped_ptr<SyncTask>(new ListChangesTask(context_.get())),
         SyncTaskManager::PRIORITY_HIGH,
         base::Bind(&SyncWorker::DidFetchChanges,
-                   weak_ptr_factory_.GetWeakPtr()));
+                   AsWeakPtr()));
     should_check_remote_change_ = false;
     listing_remote_changes_ = true;
     time_to_check_changes_ =
@@ -616,7 +612,7 @@ void SyncWorker::MaybeStartFetchChanges() {
           FROM_HERE,
           scoped_ptr<SyncTask>(new ConflictResolver(context_.get())),
           base::Bind(&SyncWorker::DidResolveConflict,
-                     weak_ptr_factory_.GetWeakPtr()));
+                     AsWeakPtr()));
     }
     return;
   }
@@ -625,7 +621,7 @@ void SyncWorker::MaybeStartFetchChanges() {
           FROM_HERE,
           scoped_ptr<SyncTask>(new ListChangesTask(context_.get())),
           base::Bind(&SyncWorker::DidFetchChanges,
-                     weak_ptr_factory_.GetWeakPtr()))) {
+                     AsWeakPtr()))) {
     should_check_remote_change_ = false;
     listing_remote_changes_ = true;
     time_to_check_changes_ =