Fix problem where app notification sync tests sometimes cant't delete temp dir

chrome/browser/extensions/app_notification_manager_sync_unittest.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 "base/bind.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/string_number_conversions.h"
 #include "chrome/browser/extensions/app_notification_manager.h"
 #include "chrome/browser/extensions/app_notification.h"
 #include "chrome/browser/sync/protocol/app_notification_specifics.pb.h"
@@ skipping 64 matching lines @@
 
     ASSERT_TRUE(temp_dir_.CreateUniqueTempDir());
     profile_.reset(new TestingProfile(temp_dir_.path()));
     model_ = new AppNotificationManager(profile_.get());
     model_->Init();
 
     WaitForFileThread();
     ASSERT_TRUE(model_->loaded());
   }
 
-  virtual void TearDown() { }
+  virtual void TearDown() {
+    WaitForFileThread();
+  }
 
   static void PostQuitToUIThread() {
     BrowserThread::PostTask(BrowserThread::UI,
                             FROM_HERE,
                             new MessageLoop::QuitTask());
   }
 
   static void WaitForFileThread() {
     BrowserThread::PostTask(BrowserThread::FILE,
                             FROM_HERE,
@@ skipping 476 matching lines @@
 
   EXPECT_EQ(3, processor()->change_list_size());
   EXPECT_TRUE(processor()->ContainsGuid(n1->guid()));
   SyncChange c1 = processor()->GetChangeByGuid(n1->guid());
   AssertSyncChange(c1, SyncChange::ACTION_DELETE, *n1);
   SyncChange c2 = processor()->GetChangeByGuid(n2->guid());
   AssertSyncChange(c2, SyncChange::ACTION_DELETE, *n2);
   SyncChange c3 = processor()->GetChangeByGuid(n3->guid());
   AssertSyncChange(c3, SyncChange::ACTION_DELETE, *n3);
 }