Save disconnect frame in the GameInformation

This information is useful to infer a winner in case the winstate is
unknown.

OpenRA.Game/GameInformation.cs

@@ -179,6 +179,9 @@ namespace OpenRA
 			/// <summary>The time when this player won or lost the game.</summary>
 			public DateTime OutcomeTimestampUtc;
 
+			/// <summary>The frame at which this player disconnected.</summary>
+			public int DisconnectFrame;
+
 			#endregion
 		}
 	}

OpenRA.Game/Network/UnitOrders.cs

@@ -39,7 +39,13 @@ namespace OpenRA.Network
 					{
 						var client = orderManager.LobbyInfo.ClientWithIndex(clientId);
 						if (client != null)
+						{
 							client.State = Session.ClientState.Disconnected;
+							var player = world?.FindPlayerByClient(client);
+							if (player != null)
+								world.OnPlayerDisconnected(player);
+						}
+
 						break;
 					}
 

OpenRA.Game/Server/Server.cs

@@ -1044,6 +1044,12 @@ namespace OpenRA.Server
 					// Send disconnected order, even if still in the lobby
 					DispatchOrdersToClients(toDrop, 0, Order.FromTargetString("Disconnected", "", true).Serialize());
 
+					if (gameInfo != null && !dropClient.IsObserver)
+					{
+						var disconnectedPlayer = gameInfo.Players.First(p => p.ClientIndex == toDrop.PlayerIndex);
+						disconnectedPlayer.DisconnectFrame = toDrop.MostRecentFrame;
+					}
+
 					LobbyInfo.Clients.RemoveAll(c => c.Index == toDrop.PlayerIndex);
 					LobbyInfo.ClientPings.RemoveAll(p => p.Index == toDrop.PlayerIndex);
 

OpenRA.Game/World.cs

@@ -552,6 +552,15 @@ namespace OpenRA
 			}
 		}
 
+		public void OnPlayerDisconnected(Player player)
+		{
+			var pi = gameInfo.GetPlayer(player);
+			if (pi == null)
+				return;
+
+			pi.DisconnectFrame = OrderManager.NetFrameNumber;
+		}
+
 		public void RequestGameSave(string filename)
 		{
 			// Allow traits to save arbitrary data that will be passed back via IGameSaveTraitData.ResolveTraitData