Add methods covering match start / end

osu.Game/Online/RealtimeMultiplayer/IMultiplayerClient.cs

@@ -46,5 +46,20 @@ namespace osu.Game.Online.RealtimeMultiplayer
         /// <param name="userId">The ID of the user performing a state change.</param>
         /// <param name="state">The new state of the user.</param>
         Task UserStateChanged(long userId, MultiplayerUserState state);
+
+        /// <summary>
+        /// Signals that a match is to be started. Users in the <see cref="MultiplayerUserState.Ready"/> state should begin loading gameplay at this point.
+        /// </summary>
+        Task LoadRequested();
+
+        /// <summary>
+        /// Signals that a match has started. All loaded users' clients should now start gameplay as soon as possible.
+        /// </summary>
+        Task MatchStarted();
+
+        /// <summary>
+        /// Signals that the match has ended, all players have finished and results are ready to be displayed.
+        /// </summary>
+        Task ResultsReady();
     }
 }

osu.Game/Online/RealtimeMultiplayer/IMultiplayerServer.cs

@@ -37,5 +37,10 @@ namespace osu.Game.Online.RealtimeMultiplayer
         /// <param name="newState">The proposed new state.</param>
         /// <exception cref="InvalidStateChange">If the state change requested is not valid, given the previous state or room state.</exception>
         Task ChangeState(MultiplayerUserState newState);
+
+        /// <summary>
+        /// As the host of a room, start the match.
+        /// </summary>
+        Task StartMatch();
     }
 }