Fix assertion starting cast_shell (breaking thread IO restrictions).

ui/events/ozone/device/device_manager_manual.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 UI_EVENTS_OZONE_DEVICE_DEVICE_MANAGER_MANUAL_H_
 #define UI_EVENTS_OZONE_DEVICE_DEVICE_MANAGER_MANUAL_H_
 
+#include <vector>
+
 #include "base/macros.h"
+#include "base/observer_list.h"
 #include "ui/events/ozone/device/device_manager.h"
 
+namespace base {
+class FilePath;
+}
+
 namespace ui {
 
 class DeviceManagerManual : public DeviceManager {
  public:
   DeviceManagerManual();
   ~DeviceManagerManual() override;
 
  private:
   // DeviceManager overrides:
   void ScanDevices(DeviceEventObserver* observer) override;
   void AddObserver(DeviceEventObserver* observer) override;
   void RemoveObserver(DeviceEventObserver* observer) override;
 
+  void OnDevicesScanned(std::vector<base::FilePath>* result);
+
+  bool have_scanned_devices_;
+  std::vector<base::FilePath> devices_;
+  ObserverList<DeviceEventObserver> observers_;
+
+  base::WeakPtrFactory<DeviceManagerManual> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(DeviceManagerManual);
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_OZONE_DEVICE_DEVICE_MANAGER_MANUAL_H_