Replace more ObserverList with base::ObserverList.

device/usb/usb_service.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_USB_USB_SERVICE_H_
 #define DEVICE_USB_USB_SERVICE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 44 matching lines @@
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
  protected:
   UsbService();
   virtual ~UsbService();
 
   void NotifyDeviceAdded(scoped_refptr<UsbDevice> device);
   void NotifyDeviceRemoved(scoped_refptr<UsbDevice> device);
 
-  ObserverList<Observer, true> observer_list_;
+  base::ObserverList<Observer, true> observer_list_;
 
  private:
   friend void base::DeletePointer<UsbService>(UsbService* service);
 
   DISALLOW_COPY_AND_ASSIGN(UsbService);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_USB_USB_SERVICE_H_