Remove MessageLoop destruction observer from hid_connection_linux.cc

device/hid/hid_service_linux.h

 // Copyright 2014 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 DEVICE_HID_HID_SERVICE_LINUX_H_
 #define DEVICE_HID_HID_SERVICE_LINUX_H_
 
 #include <memory>
 
 #include "base/compiler_specific.h"
 #include "base/files/scoped_file.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "build/build_config.h"
 #include "device/hid/hid_device_info.h"
 #include "device/hid/hid_service.h"
 
 namespace device {
 
 class HidServiceLinux : public HidService {
  public:
-  HidServiceLinux(scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner);
+  HidServiceLinux(
+      scoped_refptr<base::SequencedTaskRunner> blocking_task_runner);
   ~HidServiceLinux() override;
 
   // HidService:
   void Shutdown() override;
   void Connect(const HidDeviceId& device_id,
                const ConnectCallback& callback) override;
 
  private:
   struct ConnectParams;
   class FileThreadHelper;
 
   // These functions implement the process of locating, requesting access to and
   // opening a device. Because this operation crosses multiple threads these
   // functions are static and the necessary parameters are passed as a single
   // struct.
 #if defined(OS_CHROMEOS)
   static void OnPathOpenComplete(std::unique_ptr<ConnectParams> params,
                                  base::ScopedFD fd);
   static void OnPathOpenError(const std::string& device_path,
                               const ConnectCallback& callback,
                               const std::string& error_name,
                               const std::string& error_message);
 #else
   static void OpenOnBlockingThread(std::unique_ptr<ConnectParams> params);
 #endif
   static void FinishOpen(std::unique_ptr<ConnectParams> params);
   static void CreateConnection(std::unique_ptr<ConnectParams> params);
 
-  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
-  scoped_refptr<base::SingleThreadTaskRunner> file_task_runner_;
+  const scoped_refptr<base::SequencedTaskRunner> task_runner_;
+  const scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
 
   // The helper lives on the FILE thread and holds a weak reference back to the
   // service that owns it.
   std::unique_ptr<FileThreadHelper> helper_;
   base::WeakPtrFactory<HidServiceLinux> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(HidServiceLinux);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_HID_HID_SERVICE_LINUX_H_