CEF 146: fix cookie visitor thread assertion and update snippet URLs

- cookie.pyx: change CookieVisitor_Visit thread assertion from TID_IO to
  TID_UI — CEF 146 changed CookieVisitor::Visit to always fire on the UI
  thread (previously IO thread), causing AssertionError on every callback
- cookies.py: fix bug where OnLoadingStateChange checked "if is_loading"
  (fires on load start) instead of "if not is_loading" (fires on complete);
  update dead html-kit.com URL to https://www.google.com/
- network_cookies.py: update dead html-kit.com URL to https://www.google.com/

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: linesight

examples/snippets/cookies.py

@@ -9,7 +9,7 @@
 def main():
     cef.Initialize()
     browser = cef.CreateBrowserSync(
-        url="http://www.html-kit.com/tools/cookietester/",
+        url="https://www.google.com/",
         window_title="Cookies")
     browser.SetClientHandler(LoadHandler())
     cef.MessageLoop()
@@ -19,7 +19,7 @@ def main():
 
 class LoadHandler(object):
     def OnLoadingStateChange(self, browser, is_loading, **_):
-        if is_loading:
+        if not is_loading:
             print("Page loading complete - start visiting cookies")
             manager = cef.CookieManager.GetGlobalManager()
             # Must keep a strong reference to the CookieVisitor object
@@ -32,7 +32,7 @@ def OnLoadingStateChange(self, browser, is_loading, **_):
             # To visit cookies only for a given url uncomment the
             # code below.
             """
-            url = "http://www.html-kit.com/tools/cookietester/"
+            url = "https://www.google.com/"
             http_only_cookies = False
             result = manager.VisitUrlCookies(url, http_only_cookies,
                                              self.cookie_visitor)

examples/snippets/network_cookies.py

@@ -9,7 +9,7 @@
 def main():
     cef.Initialize()
     browser = cef.CreateBrowserSync(
-        url="http://www.html-kit.com/tools/cookietester/",
+        url="https://www.google.com/",
         window_title="Network cookies")
     browser.SetClientHandler(RequestHandler())
     cef.MessageLoop()

src/cookie.pyx

@@ -315,7 +315,7 @@ cdef public cpp_bool CookieVisitor_Visit(
     cdef PyCookie pyCookie
     cdef list pyDeleteCookie = [False]
     try:
-        assert IsThread(TID_IO), "Must be called on the IO thread"
+        assert IsThread(TID_UI), "Must be called on the UI thread"
         pyCookieVisitor = GetPyCookieVisitor(cookieVisitorId)
         pyCookie = CreatePyCookie(cookie)
         if pyCookieVisitor: