Imported Upstream version 4.8.0.309

Former-commit-id: 5f9c6ae75f295e057a7d2971f3a6df4656fa8850

mcs/class/System.Runtime.Caching/ReferenceSources/SRef.cs

@@ -1,31 +0,0 @@
-using System;
-using System.Runtime.InteropServices;
-
-namespace System.Runtime.Caching {
-    /*
-     * This class is used to retrieve the size of an object graph.
-     * Although Mono has not a way of computing this.
-     * Known problems:
-     *   - CacheMemoryMonitor does not trim the cache when it reaches its memory size limit.
-     *   - IMemoryCacheManager.UpdateCacheSize is called with incorrect size.
-     */
-    internal class SRef {
-
-//        private Object _sizedRef;
-
-        internal SRef (Object target) {
-//            _sizedRef = target;
-        }
-
-        internal long ApproximateSize {
-            get {
-                // TODO: .net uses System.SizedReference which contains approximate size after Gen 2 collection
-                return 16;
-            }
-        }
-
-        internal void Dispose() {
-
-        }
-    }
-}