WPF - Allow ToolTip timer configuration

- Can set initial show delay in xaml via existing ToolTipService e.g. ToolTipService.InitialShowDelay="100"
- If InitialShowDelay = 0 then no timer is used and ToolTip is immediately shown
- Previous delay was 500ms, new delay is the .Net default (typically 1000ms)

Related to issue #4048

CefSharp.Wpf/ChromiumWebBrowser.cs

@@ -1680,16 +1680,18 @@ private static void OnTooltipTextChanged(DependencyObject d, DependencyPropertyC
         /// <param name="newValue">new value</param>
         protected virtual void OnTooltipTextChanged(string oldValue, string newValue)
         {
-            var timer = tooltipTimer;
-            if (timer == null)
+            // There are cases where oldValue is null and newValue is string.Empty
+            // and vice versa, simply ignore when string.IsNullOrEmpty for both.
+            if (string.IsNullOrEmpty(oldValue) && string.IsNullOrEmpty(newValue))
             {
                 return;
             }
 
-            // There are cases where oldValue is null and newValue is string.Empty
-            // and vice versa, simply ignore when string.IsNullOrEmpty for both.
-            if (string.IsNullOrEmpty(oldValue) && string.IsNullOrEmpty(newValue))
+            var timer = tooltipTimer;
+            if (timer == null)
             {
+                OpenOrCloseToolTip(newValue);
+
                 return;
             }
 
@@ -2151,14 +2153,18 @@ private void OnIsVisibleChanged(object sender, DependencyPropertyChangedEventArg
         /// <param name="routedEventArgs">The <see cref="RoutedEventArgs"/> instance containing the event data.</param>
         private void OnLoaded(object sender, RoutedEventArgs routedEventArgs)
         {
-            // TODO: Consider making the delay here configurable.
-            tooltipTimer = new DispatcherTimer(
-                TimeSpan.FromSeconds(0.5),
-                DispatcherPriority.Render,
-                OnTooltipTimerTick,
-                Dispatcher
-                );
-            tooltipTimer.IsEnabled = false;
+            var initialShowDelay = ToolTipService.GetInitialShowDelay(this);
+
+            if (initialShowDelay > 0)
+            {
+                tooltipTimer = new DispatcherTimer(
+                    TimeSpan.FromMilliseconds(initialShowDelay),
+                    DispatcherPriority.Render,
+                    OnTooltipTimerTick,
+                    Dispatcher
+                    );
+                tooltipTimer.IsEnabled = false;
+            }
 
             //Initial value for screen location
             browserScreenLocation = GetBrowserScreenLocation();