A Kinect version of sub class of the ObserverBase

using System;
using System.Collections.Generic;
using System.Reactive.Disposables;
using System.Reactive.Linq;
using Microsoft.Kinect;
using Microsoft.Kinect.Toolkit;
using Microsoft.Practices.EnterpriseLibrary.Common.Utility;

namespace Foo
{
    /// <summary>
    /// An abstract base class of classes that observes a Kinect's XxxFrameReady event(s).
    /// </summary>
    public abstract class KinectObserverBase : ObserverBase
    {
        private readonly KinectSensorChooser _sensorChooser;

        /// <summary>
        /// Initializes a new instance of the <see cref="KinectObserverBase"/> class.
        /// </summary>
        /// <exception cref="System.ArgumentNullException">
        /// <paramref name="sensorChooser"/> is <c>null</c>.
        /// </exception>
        protected KinectObserverBase(KinectSensorChooser sensorChooser)
        {
            Guard.ArgumentNotNull(sensorChooser, "sensorChooser");
            _sensorChooser = sensorChooser;
        }

        /// <summary>
        /// Subscribes to observable subject(s).
        /// </summary>
        /// <returns>
        /// The subscription(s). Typically, the disposable returned from the Subscribe extension method of
        /// <seealso cref="IObservable{T}" /> should be returned.
        /// </returns>
        protected override IDisposable SubscribeToObservable()
        {
            var subscriptions = new List<IDisposable>();

            var kinect = _sensorChooser.Kinect;
            if (kinect != null)
                subscriptions.Add(SubscribeToFrameReady(kinect));

            subscriptions.Add(SubscribeToKinectChanged());

            return new CompositeDisposable(subscriptions);
        }

        /// <summary>
        /// Subscribes to frame ready event(s) of the specified <seealso cref="KinectSensor"/>.
        /// To subscribe, Rx should be used in derived classes.
        /// </summary>
        /// <param name="kinect">The <seealso cref="KinectSensor"/>.</param>
        /// <returns>
        /// The subscription(s) to the frame ready event(s) of the <paramref name="kinect"/>.
        /// </returns>
        protected abstract IDisposable SubscribeToFrameReady(KinectSensor kinect);

        private IDisposable SubscribeToKinectChanged()
        {
            return Observable.FromEventPattern<KinectChangedEventArgs>(eh => _sensorChooser.KinectChanged += eh,
                                                                       eh => _sensorChooser.KinectChanged -= eh)
                             .Subscribe(ep =>
                             {
                                 StopObserving();
                                 StartObserving();
                             });
        }
    }
}