Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/Instrumentation/PageInstrumentationService.cs

@@ -0,0 +1,25 @@
+using System.Collections.Generic;
+
+namespace System.Web.Instrumentation
+{
+    public sealed class PageInstrumentationService {
+        /// <summary>
+        /// Gets or sets a boolean indicating if instrumentation is active for the entire application
+        /// </summary>
+        /// <remarks>
+        /// Page Instrumentation is a per-request service, and may not be active for a particular request, however this flag MUST be true
+        /// for any request to use Page Instrumentation.
+        /// </remarks>
+        public static bool IsEnabled { get; set; }
+
+        private IList<PageExecutionListener> _executionListeners = new List<PageExecutionListener>();
+
+        /// <summary>
+        /// Gets a list of listeners which are subscribed to the page execution process.
+        /// </summary>
+        /// <remarks>
+        /// Guaranteed not to be null, but MAY be an empty list.
+        /// </remarks>
+        public IList<PageExecutionListener> ExecutionListeners { get { return _executionListeners; } }
+    }
+}