Fixed the CustomResourceHandler demo

- Added TCEFSentinel to more demos

demos/Lazarus/JavaScript/JSSimpleExtension/JSSimpleExtension.lps

@@ -22,15 +22,15 @@
         <ResourceBaseClass Value="Form"/>
         <IsVisibleTab Value="True"/>
         <EditorIndex Value="1"/>
-        <TopLine Value="122"/>
-        <CursorPos Y="143"/>
+        <TopLine Value="209"/>
+        <CursorPos X="22" Y="234"/>
         <UsageCount Value="20"/>
         <Loaded Value="True"/>
         <LoadedDesigner Value="True"/>
         <DefaultSyntaxHighlighter Value="Delphi"/>
       </Unit1>
     </Units>
-    <JumpHistory Count="4" HistoryIndex="3">
+    <JumpHistory Count="7" HistoryIndex="6">
       <Position1>
         <Filename Value="uJSSimpleExtension.pas"/>
       </Position1>
@@ -46,6 +46,18 @@
         <Filename Value="uJSSimpleExtension.pas"/>
         <Caret Line="161" Column="39" TopLine="138"/>
       </Position4>
+      <Position5>
+        <Filename Value="uJSSimpleExtension.pas"/>
+        <Caret Line="143" TopLine="122"/>
+      </Position5>
+      <Position6>
+        <Filename Value="uJSSimpleExtension.pas"/>
+        <Caret Line="148" TopLine="127"/>
+      </Position6>
+      <Position7>
+        <Filename Value="uJSSimpleExtension.pas"/>
+        <Caret Line="233" TopLine="215"/>
+      </Position7>
     </JumpHistory>
     <RunParams>
       <FormatVersion Value="2"/>

demos/Lazarus/JavaScript/JSSimpleExtension/uJSSimpleExtension.lfm

@@ -69,4 +69,9 @@ object JSSimpleExtensionFrm: TJSSimpleExtensionFrm
     left = 32
     top = 288
   end
+  object CEFSentinel1: TCEFSentinel
+    OnClose = CEFSentinel1Close
+    left = 32
+    top = 352
+  end
 end

demos/Lazarus/JavaScript/JSSimpleExtension/uJSSimpleExtension.pas

@@ -52,16 +52,21 @@ uses
   Controls, Forms, Dialogs, StdCtrls, ExtCtrls, ComCtrls,
   {$ENDIF}
   uCEFChromium, uCEFWindowParent, uCEFInterfaces, uCEFApplication, uCEFTypes, uCEFConstants,
-  uCEFWinControl;
+  uCEFWinControl, uCEFSentinel;
 
 type
+
+  { TJSSimpleExtensionFrm }
+
   TJSSimpleExtensionFrm = class(TForm)
+    CEFSentinel1: TCEFSentinel;
     NavControlPnl: TPanel;
     Edit1: TEdit;
     GoBtn: TButton;
     CEFWindowParent1: TCEFWindowParent;
     Chromium1: TChromium;
     Timer1: TTimer;
+    procedure CEFSentinel1Close(Sender: TObject);
     procedure FormShow(Sender: TObject);
     procedure GoBtnClick(Sender: TObject);
     procedure Chromium1AfterCreated(Sender: TObject; const browser: ICefBrowser);
@@ -117,7 +122,8 @@ uses
 // =================
 // 1. FormCloseQuery sets CanClose to FALSE calls TChromium.CloseBrowser which triggers the TChromium.OnClose event.
 // 2. TChromium.OnClose sends a CEFBROWSER_DESTROY message to destroy CEFWindowParent1 in the main thread, which triggers the TChromium.OnBeforeClose event.
-// 3. TChromium.OnBeforeClose sets FCanClose := True and sends WM_CLOSE to the form.
+// 3. TChromium.OnBeforeClose calls TCEFSentinel.Start, which will trigger TCEFSentinel.OnClose when the renderer processes are closed.
+// 4. TCEFSentinel.OnClose sets FCanClose := True and sends WM_CLOSE to the form.
 
 procedure GlobalCEFApp_OnWebKitInitializedEvent;
 var
@@ -173,6 +179,12 @@ begin
   if not(Chromium1.CreateBrowser(CEFWindowParent1, '')) then Timer1.Enabled := True;
 end;
 
+procedure TJSSimpleExtensionFrm.CEFSentinel1Close(Sender: TObject);
+begin
+  FCanClose := True;
+  PostMessage(Handle, WM_CLOSE, 0, 0);
+end;
+
 procedure TJSSimpleExtensionFrm.WMMove(var aMessage : TWMMove);
 begin
   inherited;
@@ -219,8 +231,7 @@ end;
 procedure TJSSimpleExtensionFrm.Chromium1BeforeClose(
   Sender: TObject; const browser: ICefBrowser);
 begin
-  FCanClose := True;
-  PostMessage(Handle, WM_CLOSE, 0, 0);
+  CEFSentinel1.Start;
 end;
 
 procedure TJSSimpleExtensionFrm.Chromium1Close(