Extracted UsbService as interface.

components/usb_service/usb_device.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 COMPONENTS_USB_SERVICE_USB_DEVICE_H_
 #define COMPONENTS_USB_SERVICE_USB_DEVICE_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 43 matching lines @@
   // Closing a closed handle is a safe
   // Blocking method. Must be called on FILE thread.
   virtual bool Close(scoped_refptr<UsbDeviceHandle> handle);
 
   // Lists the interfaces provided by the device and fills the given
   // UsbConfigDescriptor.
   // Blocking method. Must be called on FILE thread.
   virtual scoped_refptr<UsbConfigDescriptor> ListInterfaces();
 
  protected:
-  friend class UsbService;
+  friend class UsbServiceImpl;
   friend class base::RefCountedThreadSafe<UsbDevice>;
 
   // Called by UsbService only;
   UsbDevice(scoped_refptr<UsbContext> context,
             PlatformUsbDevice platform_device,
             uint16 vendor_id,
             uint16 product_id,
             uint32 unique_id);
 
   // Constructor called in test only.
@@ skipping 17 matching lines @@
   HandlesVector handles_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(UsbDevice);
 };
 
 }  // namespace usb_service
 
 #endif  // COMPONENTS_USB_SERVICE_USB_DEVICE_H_