Check that extensions::HidDeviceManager is used from the FILE thread.

extensions/browser/api/hid/hid_device_manager.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_BROWSER_API_HID_HID_DEVICE_MANAGER_H_
 #define EXTENSIONS_BROWSER_API_HID_HID_DEVICE_MANAGER_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 33 matching lines @@
 
   bool GetDeviceInfo(int resource_id, device::HidDeviceInfo* device_info);
 
   bool HasPermission(const Extension* extension,
                      const device::HidDeviceInfo& device_info);
 
  private:
   friend class BrowserContextKeyedAPIFactory<HidDeviceManager>;
 
   static const char* service_name() { return "HidDeviceManager"; }
+  static bool IsCalledOnValidThread();
 
   void UpdateDevices();
 
-  base::ThreadChecker thread_checker_;
-
   int next_resource_id_;
 
   typedef std::map<int, device::HidDeviceId> ResourceIdToDeviceIdMap;
   typedef std::map<device::HidDeviceId, int> DeviceIdToResourceIdMap;
 
   ResourceIdToDeviceIdMap device_ids_;
   DeviceIdToResourceIdMap resource_ids_;
 
   DISALLOW_COPY_AND_ASSIGN(HidDeviceManager);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_API_HID_HID_DEVICE_MANAGER_H_