Add support for vote-to-skip in multiplayer

osu.Game/Online/Multiplayer/MultiplayerClient.cs

@@ -131,6 +131,9 @@ namespace osu.Game.Online.Multiplayer
         public event Action<int, long>? MatchmakingItemDeselected;
         public event Action<MatchRoomState>? MatchRoomStateChanged;
 
+        public event Action<int>? UserVotedToSkip;
+        public event Action? VoteToSkipPassed;
+
         /// <summary>
         /// Whether the <see cref="MultiplayerClient"/> is currently connected.
         /// This is NOT thread safe and usage should be scheduled.
@@ -521,6 +524,12 @@ namespace osu.Game.Online.Multiplayer
                         break;
                 }
 
+                if (state == MultiplayerRoomState.Playing)
+                {
+                    foreach (var user in Room.Users)
+                        user.VotedToSkip = false;
+                }
+
                 RoomUpdated?.Invoke();
             });
 
@@ -920,12 +929,33 @@ namespace osu.Game.Online.Multiplayer
 
         Task IMultiplayerClient.UserVotedToSkip(int userId)
         {
-            throw new NotImplementedException();
+            handleRoomRequest(() =>
+            {
+                Debug.Assert(Room != null);
+
+                var user = Room.Users.SingleOrDefault(u => u.UserID == userId);
+
+                // TODO: user should NEVER be null here, see https://github.com/ppy/osu/issues/17713.
+                if (user == null)
+                    return;
+
+                user.VotedToSkip = true;
+
+                UserVotedToSkip?.Invoke(userId);
+            });
+
+            return Task.CompletedTask;
         }
 
         Task IMultiplayerClient.VoteToSkipPassed()
         {
-            throw new NotImplementedException();
+            handleRoomRequest(() =>
+            {
+                Debug.Assert(Room != null);
+                VoteToSkipPassed?.Invoke();
+            });
+
+            return Task.CompletedTask;
         }
 
         /// <summary>

osu.Game/Online/Multiplayer/OnlineMultiplayerClient.cs

@@ -70,7 +70,8 @@ namespace osu.Game.Online.Multiplayer
                     connection.On<MultiplayerPlaylistItem>(nameof(IMultiplayerClient.PlaylistItemAdded), ((IMultiplayerClient)this).PlaylistItemAdded);
                     connection.On<long>(nameof(IMultiplayerClient.PlaylistItemRemoved), ((IMultiplayerClient)this).PlaylistItemRemoved);
                     connection.On<MultiplayerPlaylistItem>(nameof(IMultiplayerClient.PlaylistItemChanged), ((IMultiplayerClient)this).PlaylistItemChanged);
-                    connection.On(nameof(IStatefulUserHubClient.DisconnectRequested), ((IMultiplayerClient)this).DisconnectRequested);
+                    connection.On<int>(nameof(IMultiplayerClient.UserVotedToSkip), ((IMultiplayerClient)this).UserVotedToSkip);
+                    connection.On(nameof(IMultiplayerClient.VoteToSkipPassed), ((IMultiplayerClient)this).VoteToSkipPassed);
 
                     connection.On(nameof(IMatchmakingClient.MatchmakingQueueJoined), ((IMatchmakingClient)this).MatchmakingQueueJoined);
                     connection.On(nameof(IMatchmakingClient.MatchmakingQueueLeft), ((IMatchmakingClient)this).MatchmakingQueueLeft);
@@ -80,6 +81,8 @@ namespace osu.Game.Online.Multiplayer
                     connection.On<MatchmakingQueueStatus>(nameof(IMatchmakingClient.MatchmakingQueueStatusChanged), ((IMatchmakingClient)this).MatchmakingQueueStatusChanged);
                     connection.On<int, long>(nameof(IMatchmakingClient.MatchmakingItemSelected), ((IMatchmakingClient)this).MatchmakingItemSelected);
                     connection.On<int, long>(nameof(IMatchmakingClient.MatchmakingItemDeselected), ((IMatchmakingClient)this).MatchmakingItemDeselected);
+
+                    connection.On(nameof(IStatefulUserHubClient.DisconnectRequested), ((IMultiplayerClient)this).DisconnectRequested);
                 };
 
                 IsConnected.BindTo(connector.IsConnected);
@@ -314,7 +317,12 @@ namespace osu.Game.Online.Multiplayer
 
         public override Task VoteToSkip()
         {
-            throw new NotImplementedException();
+            if (!IsConnected.Value)
+                return Task.CompletedTask;
+
+            Debug.Assert(connection != null);
+
+            return connection.InvokeAsync(nameof(IMultiplayerServer.VoteToSkip));
         }
 
         public override Task DisconnectInternal()

osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerPlayer.cs

@@ -56,7 +56,6 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
             {
                 AllowPause = false,
                 AllowRestart = false,
-                AllowSkipping = room.AutoSkip,
                 AutomaticallySkipIntro = room.AutoSkip,
                 ShowLeaderboard = true,
             })
@@ -121,6 +120,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
 
             client.GameplayStarted += onGameplayStarted;
             client.ResultsReady += onResultsReady;
+            client.VoteToSkipPassed += onVoteToSkipPassed;
 
             ScoreProcessor.HasCompleted.BindValueChanged(_ =>
             {
@@ -219,6 +219,17 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
             await Task.WhenAny(resultsReady.Task, Task.Delay(TimeSpan.FromSeconds(60))).ConfigureAwait(false);
         }
 
+        protected override void RequestIntroSkip()
+        {
+            // No base call because we aren't skipping yet.
+            client.VoteToSkip();
+        }
+
+        private void onVoteToSkipPassed()
+        {
+            Schedule(PerformIntroSkip);
+        }
+
         protected override ResultsScreen CreateResults(ScoreInfo score)
         {
             Debug.Assert(Room.RoomID != null);
@@ -242,6 +253,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
             {
                 client.GameplayStarted -= onGameplayStarted;
                 client.ResultsReady -= onResultsReady;
+                client.VoteToSkipPassed -= onVoteToSkipPassed;
             }
         }
     }

osu.Game/Screens/Play/Player.cs

@@ -502,7 +502,7 @@ namespace osu.Game.Screens.Play
                     DrawableRuleset.Cursor?.CreateProxy() ?? new Container(),
                     skipIntroOverlay = new SkipOverlay(DrawableRuleset.GameplayStartTime)
                     {
-                        RequestSkip = performUserRequestedSkip
+                        RequestSkip = RequestIntroSkip
                     },
                     skipOutroOverlay = new SkipOverlay(GameplayState.Storyboard.LatestEventTime ?? 0)
                     {
@@ -701,7 +701,12 @@ namespace osu.Game.Screens.Play
             return true;
         }
 
-        private void performUserRequestedSkip()
+        protected virtual void RequestIntroSkip()
+        {
+            PerformIntroSkip();
+        }
+
+        protected void PerformIntroSkip()
         {
             // user requested skip
             // disable sample playback to stop currently playing samples and perform skip

osu.Game/Tests/Visual/Multiplayer/TestMultiplayerClient.cs

@@ -563,7 +563,7 @@ namespace osu.Game.Tests.Visual.Multiplayer
 
         public override Task VoteToSkip()
         {
-            throw new NotImplementedException();
+            return Task.CompletedTask;
         }
 
         protected override Task<MultiplayerRoom> CreateRoomInternal(MultiplayerRoom room)