Do not observe MessageLoop destruction from ModelSafeWorker.

components/password_manager/sync/browser/password_model_worker.cc

 // Copyright (c) 2015 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 "components/password_manager/sync/browser/password_model_worker.h"
 
 #include "base/bind.h"
-#include "base/memory/ref_counted.h"
+#include "base/callback.h"
 #include "base/synchronization/waitable_event.h"
 #include "components/password_manager/core/browser/password_store.h"
 #include "components/sync/base/scoped_event_signal.h"
 
 namespace browser_sync {
 
 namespace {
 
 void CallDoWorkAndSignalEvent(const syncer::WorkCallback& work,
                               syncer::ScopedEventSignal scoped_event_signal,
                               syncer::SyncerError* error_info) {
   *error_info = work.Run();
   // The event in |scoped_event_signal| is signaled at the end of this scope.
 }
 
 }  // namespace
 
 PasswordModelWorker::PasswordModelWorker(
-    const scoped_refptr<password_manager::PasswordStore>& password_store,
-    syncer::WorkerLoopDestructionObserver* observer)
-    : syncer::ModelSafeWorker(observer), password_store_(password_store) {
+    const scoped_refptr<password_manager::PasswordStore>& password_store)
+    : password_store_(password_store) {
   DCHECK(password_store.get());
 }
 
-void PasswordModelWorker::RegisterForLoopDestruction() {
-  base::AutoLock lock(password_store_lock_);
-  password_store_->ScheduleTask(base::Bind(
-      &PasswordModelWorker::RegisterForPasswordLoopDestruction, this));
-}
-
 syncer::SyncerError PasswordModelWorker::DoWorkAndWaitUntilDoneImpl(
     const syncer::WorkCallback& work) {
   syncer::SyncerError error = syncer::UNSET;
 
   // Signaled when the task is deleted, i.e. after it runs or when it is
   // abandoned.
   base::WaitableEvent work_done_or_abandoned(
       base::WaitableEvent::ResetPolicy::AUTOMATIC,
       base::WaitableEvent::InitialState::NOT_SIGNALED);
 
@@ skipping 15 matching lines @@
     error = syncer::CANNOT_DO_WORK;
   return error;
 }
 
 syncer::ModelSafeGroup PasswordModelWorker::GetModelSafeGroup() {
   return syncer::GROUP_PASSWORD;
 }
 
 PasswordModelWorker::~PasswordModelWorker() {}
 
-void PasswordModelWorker::RegisterForPasswordLoopDestruction() {
-  SetWorkingLoopToCurrent();
-}
-
 void PasswordModelWorker::RequestStop() {
   ModelSafeWorker::RequestStop();
 
   base::AutoLock lock(password_store_lock_);
   password_store_ = NULL;
 }
 
 }  // namespace browser_sync