How do I clear the cache and cookies for an embedded Chromium browser?

DCEF1:

To delete cookies in DCEF1 wrapper there's the DeleteCookies function in ICefCookieManager manager interface. However, I've tried the following code to delete all cookies, but it always failed to me:

procedure TForm1.Button1Click(Sender: TObject);
var
  CookieManager: ICefCookieManager;
begin
  CookieManager := TCefCookieManagerRef.GetGlobalManager;
  if not CookieManager.DeleteCookies('', '') then
    ShowMessage('DeleteCookies failed!');
end;

Fortunately, there is another option to delete cookies using this cookie manager. Visit all of them and in the visitor function assign True to the deleteCookie output parameter. Be careful with getting cookie manager, it's created the first time you navigate somewhere (the GetGlobalManager class function is unsafe, it's not properly handled for unexpected result), so be sure you'll use this code after navigation:

procedure TForm1.Button1Click(Sender: TObject);
var
  CookieManager: ICefCookieManager;
begin
  CookieManager := TCefCookieManagerRef.GetGlobalManager;
  CookieManager.VisitAllCookiesProc(
    function(const name, value, domain, path: ustring; secure, httponly,
      hasExpires: Boolean; const creation, lastAccess, expires: TDateTime;
      count, total: Integer; out deleteCookie: Boolean): Boolean
    begin
      deleteCookie := True;
      ShowMessage('A cookie from domain ' + domain + ' will be unmercifully ' +
        'deleted!');
    end
  );
end;

DCEF3:

In DCEF3 wrapper you can use the following. Credit goes to Eric Santos:

type
  CefTask = class(TCefTaskOwn)
    procedure Execute; override;
  end;

procedure CefTask.Execute;
var
  CookieManager: ICefCookieManager;
begin
  CookieManager := TCefCookieManagerRef.Global;
  CookieManager.DeleteCookies('', '');
end;

procedure ClearCookies;
var
  Task: CefTask;
begin
  Task := CefTask.Create;
  CefPostTask(TID_IO, Task);
end;