Cleanups and xmldoc additions

osu.Game/Database/IHasFiles.cs

@@ -0,0 +1,13 @@
+using System.Collections.Generic;
+
+namespace osu.Game.Database
+{
+    /// <summary>
+    /// A model that contains a list of files it is responsible for.
+    /// </summary>
+    /// <typeparam name="TFile">The model representing a file.</typeparam>
+    public interface IHasFiles<TFile>
+    {
+        List<TFile> Files { get; set; }
+    }
+}

osu.Game/Database/ISoftDelete.cs

@@ -3,8 +3,14 @@
 
 namespace osu.Game.Database
 {
+    /// <summary>
+    /// A model that can be deleted from user's view without being instantly lost.
+    /// </summary>
     public interface ISoftDelete
     {
+        /// <summary>
+        /// Whether this model is marked for future deletion.
+        /// </summary>
         bool DeletePending { get; set; }
     }
 }

osu.Game/Database/MutableDatabaseBackedStore.cs

@@ -83,11 +83,7 @@ namespace osu.Game.Database
 
         protected virtual IQueryable<T> AddIncludesForDeletion(IQueryable<T> query) => query;
 
-        protected virtual void Purge(List<T> items, OsuDbContext context)
-        {
-            // cascades down to beatmaps.
-            context.RemoveRange(items);
-        }
+        protected virtual void Purge(List<T> items, OsuDbContext context) => context.RemoveRange(items);
 
         /// <summary>
         /// Purge items in a pending delete state.