Add CleanupElement like CefSharp.Wpf.

CefSharp.Wpf.HwndHost/ChromiumWebBrowser.cs

@@ -665,6 +665,12 @@ private void PresentationSourceChangedHandler(object sender, SourceChangedEventA
                     window.StateChanged += OnWindowStateChanged;
                     window.LocationChanged += OnWindowLocationChanged;
                     sourceWindow = window;
+
+                    // If CleanupElement is null, set the CleanupElement to the new window that the browser is moved in.
+                    if (CleanupElement == null)
+                    {
+                        CleanupElement = window;
+                    }
                 }
             }
             else if (args.OldSource != null)
@@ -676,6 +682,12 @@ private void PresentationSourceChangedHandler(object sender, SourceChangedEventA
                     window.StateChanged -= OnWindowStateChanged;
                     window.LocationChanged -= OnWindowLocationChanged;
                     sourceWindow = null;
+
+                    // If CleanupElement is the old Window that the browser is moved out of, set CleanupElement to null.
+                    if (CleanupElement == window)
+                    {
+                        CleanupElement = null;
+                    }
                 }
             }
         }
@@ -898,6 +910,11 @@ private void InternalDispose(bool disposing)
 
                 browser = null;
 
+                if (CleanupElement != null)
+                {
+                    CleanupElement.Unloaded -= OnCleanupElementUnloaded;
+                }
+
                 managedCefBrowserAdapter?.Dispose();
                 managedCefBrowserAdapter = null;
             }
@@ -1333,6 +1350,69 @@ public double ZoomLevelIncrement
         public static readonly DependencyProperty ZoomLevelIncrementProperty =
             DependencyProperty.Register(nameof(ZoomLevelIncrement), typeof(double), typeof(ChromiumWebBrowser), new PropertyMetadata(0.10));
 
+        /// <summary>
+        /// The CleanupElement Controls when the BrowserResources will be cleaned up.
+        /// The ChromiumWebBrowser will register on Unloaded of the provided Element and dispose all resources when that handler is called.
+        /// By default the cleanup element is the Window that contains the ChromiumWebBrowser.
+        /// if you want cleanup to happen earlier provide another FrameworkElement.
+        /// Be aware that this Control is not usable anymore after cleanup is done.
+        /// </summary>
+        /// <value>The cleanup element.</value>
+        public FrameworkElement CleanupElement
+        {
+            get { return (FrameworkElement)GetValue(CleanupElementProperty); }
+            set { SetValue(CleanupElementProperty, value); }
+        }
+
+        /// <summary>
+        /// The cleanup element property
+        /// </summary>
+        public static readonly DependencyProperty CleanupElementProperty =
+            DependencyProperty.Register(nameof(CleanupElement), typeof(FrameworkElement), typeof(ChromiumWebBrowser), new PropertyMetadata(null, OnCleanupElementChanged));
+
+        /// <summary>
+        /// Handles the <see cref="E:CleanupElementChanged" /> event.
+        /// </summary>
+        /// <param name="sender">The sender.</param>
+        /// <param name="args">The <see cref="DependencyPropertyChangedEventArgs"/> instance containing the event data.</param>
+        private static void OnCleanupElementChanged(DependencyObject sender, DependencyPropertyChangedEventArgs args)
+        {
+            var owner = (ChromiumWebBrowser)sender;
+            var oldValue = (FrameworkElement)args.OldValue;
+            var newValue = (FrameworkElement)args.NewValue;
+
+            owner.OnCleanupElementChanged(oldValue, newValue);
+        }
+
+        /// <summary>
+        /// Called when [cleanup element changed].
+        /// </summary>
+        /// <param name="oldValue">The old value.</param>
+        /// <param name="newValue">The new value.</param>
+        protected virtual void OnCleanupElementChanged(FrameworkElement oldValue, FrameworkElement newValue)
+        {
+            if (oldValue != null)
+            {
+                oldValue.Unloaded -= OnCleanupElementUnloaded;
+            }
+
+            if (newValue != null)
+            {
+                newValue.Unloaded += OnCleanupElementUnloaded;
+            }
+        }
+
+
+        /// <summary>
+        /// Handles the <see cref="E:CleanupElementUnloaded" /> event.
+        /// </summary>
+        /// <param name="sender">The sender.</param>
+        /// <param name="e">The <see cref="RoutedEventArgs"/> instance containing the event data.</param>
+        private void OnCleanupElementUnloaded(object sender, RoutedEventArgs e)
+        {
+            Dispose();
+        }
+
         /// <summary>
         /// The text that will be displayed as a ToolTip
         /// </summary>