Remove DeviceMonitorLinux::WillDestroyCurrentMessageLoop().

extensions/shell/browser/shell_device_client.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 EXTENSIONS_SHELL_BROWSER_SHELL_DEVICE_CLIENT_H_
 #define EXTENSIONS_SHELL_BROWSER_SHELL_DEVICE_CLIENT_H_
 
 #include <memory>
 
-#include "base/compiler_specific.h"
+#include "base/logging.h"
 #include "base/macros.h"
 #include "device/base/device_client.h"
 
 namespace extensions {
 
 // Implementation of device::DeviceClient that returns //device API service
 // singletons appropriate for use within app shell.
 class ShellDeviceClient : device::DeviceClient {
  public:
   ShellDeviceClient();
   ~ShellDeviceClient() override;
 
+  // Must be called before the destructor, when the FILE thread is still alive.
+  void Shutdown();
+
   // device::DeviceClient implementation
   device::UsbService* GetUsbService() override;
   device::HidService* GetHidService() override;
 
  private:
+#if DCHECK_IS_ON()
+  bool did_shutdown_ = false;
+#endif
+
   std::unique_ptr<device::HidService> hid_service_;
   std::unique_ptr<device::UsbService> usb_service_;
 
   DISALLOW_COPY_AND_ASSIGN(ShellDeviceClient);
 };
 
 }
 
 #endif  // EXTENSIONS_SHELL_BROWSER_SHELL_DEVICE_CLIENT_H_