Automated IWYU fix for TaskRunner includes.

chrome/browser/password_manager/password_store_mac.h

 // 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.
 
 #ifndef CHROME_BROWSER_PASSWORD_MANAGER_PASSWORD_STORE_MAC_H_
 #define CHROME_BROWSER_PASSWORD_MANAGER_PASSWORD_STORE_MAC_H_
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/callback_forward.h"
 #include "base/macros.h"
+#include "base/single_thread_task_runner.h"
 #include "base/threading/thread.h"
 #include "components/password_manager/core/browser/login_database.h"
 #include "components/password_manager/core/browser/password_store.h"
 
 namespace crypto {
 class AppleKeychain;
 }
 
 namespace password_manager {
 class LoginDatabase;
@@ skipping 124 matching lines @@
   std::unique_ptr<crypto::AppleKeychain> keychain_;
 
   // The login metadata SQL database. The caller is resonsible for initializing
   // it.
   password_manager::LoginDatabase* login_metadata_db_;
 
   DISALLOW_COPY_AND_ASSIGN(PasswordStoreMac);
 };
 
 #endif  // CHROME_BROWSER_PASSWORD_MANAGER_PASSWORD_STORE_MAC_H_