Add property Cef.IsShutdown to allow checks for the shutdown state of Cef runtime (#3782) (#3783)

Author: jozefizso

CefSharp.Core.Runtime/Cef.h

@@ -94,6 +94,16 @@ namespace CefSharp
                 }
             }
 
+            /// <summary>Gets a value that indicates whether CefSharp was shutdown.</summary>
+            /// <value>true if CefSharp was shutdown; otherwise, false.</value>
+            static property bool IsShutdown
+            {
+                bool get()
+                {
+                    return _hasShutdown;
+                }
+            }
+
             /// <summary>Gets a value that indicates the version of CefSharp currently being used.</summary>
             /// <value>The CefSharp version.</value>
             static property String^ CefSharpVersion

CefSharp.Core/Cef.cs

@@ -47,6 +47,13 @@ public static bool IsInitialized
             get { return Core.Cef.IsInitialized; }
         }
 
+        /// <summary>Gets a value that indicates whether CefSharp was shutdown.</summary>
+        /// <value>true if CefSharp was shutdown; otherwise, false.</value>
+        public static bool IsShutdown
+        {
+            get { return Core.Cef.IsShutdown; }
+        }
+
         /// <summary>Gets a value that indicates the version of CefSharp currently being used.</summary>
         /// <value>The CefSharp version.</value>
         public static string CefSharpVersion