Address requested changes and fix some warnings

MediaBrowser.Controller/SyncPlay/PlaybackRequests/BufferGroupRequest.cs

@@ -0,0 +1,46 @@
+using System;
+using System.Threading;
+using MediaBrowser.Controller.Session;
+using MediaBrowser.Model.SyncPlay;
+
+namespace MediaBrowser.Controller.SyncPlay
+{
+    /// <summary>
+    /// Class BufferGroupRequest.
+    /// </summary>
+    public class BufferGroupRequest : IGroupPlaybackRequest
+    {
+        /// <summary>
+        /// Gets or sets when the request has been made by the client.
+        /// </summary>
+        /// <value>The date of the request.</value>
+        public DateTime When { get; set; }
+
+        /// <summary>
+        /// Gets or sets the position ticks.
+        /// </summary>
+        /// <value>The position ticks.</value>
+        public long PositionTicks { get; set; }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether the client playback is unpaused.
+        /// </summary>
+        /// <value>The client playback status.</value>
+        public bool IsPlaying { get; set; }
+
+        /// <summary>
+        /// Gets or sets the playlist item identifier of the playing item.
+        /// </summary>
+        /// <value>The playlist item identifier.</value>
+        public string PlaylistItemId { get; set; }
+
+        /// <inheritdoc />
+        public PlaybackRequestType Type { get; } = PlaybackRequestType.Buffer;
+
+        /// <inheritdoc />
+        public void Apply(IGroupStateContext context, IGroupState state, SessionInfo session, CancellationToken cancellationToken)
+        {
+            state.HandleRequest(context, state.Type, this, session, cancellationToken);
+        }
+    }
+}