Update GetCookieManager bug and reopen issue (#429)

Author: cztomczak

api/RequestHandler.md

@@ -206,8 +206,8 @@ is the URL of the top-level frame. Cookies managers can be unique
 per browser or shared across multiple browsers. The global cookie
 manager will be used if this method returns None.
 
-**IMPORTANT**: In some cases the `browser` parameter can be
-None, so you should handle such case.
+**IMPORTANT**: In some cases this callback is not called due to a
+race condition. See Issue [#429](../../../issues/429) for details.
 
 To successfully implement separate cookie manager per browser session,
 you have to set ApplicationSettings.`unique_request_context_per_browser`

docs/Migration-guide.md

@@ -378,9 +378,9 @@ See a complete list of flags in the description of
 cef.Request.[GetFlags](../api/Request.md#getflags) method.
 
 
-## v66+ RequestHandler.GetCookieManager 'browser' param may be None
+## v66+ RequestHandler.GetCookieManager not getting called in some cases
 
-In some cases in RequestHandler.[GetCookieManager](../api/RequestHandler.md#getcookiemanager)
-callback, the `browser` parameter may be None due to a race condition.
-See Issue [#429](../../../issues/429) for details.
+In some cases the RequestHandler.[GetCookieManager](../api/RequestHandler.md#getcookiemanager)
+callback is not getting called due to a race condition.
+This bug is to be fixed in Issue [#429](../../../issues/429).
 

src/handlers/request_handler.pyx

@@ -291,14 +291,13 @@ cdef public CefRefPtr[CefCookieManager] RequestHandler_GetCookieManager(
     cdef object clientCallback
     cdef PyCookieManager returnValue
     try:
-        if cefBrowser.get():
-            pyBrowser = GetPyBrowser(cefBrowser, "GetCookieManager")
-        else:
-            pyBrowser = None
+        if not cefBrowser.get():
+            # Bug: In some cases due to a race condition the browser
+            #      may be NULL. Issue #429.
+            return <CefRefPtr[CefCookieManager]>NULL
+        pyBrowser = GetPyBrowser(cefBrowser, "GetCookieManager")
         pyMainUrl = CefToPyString(cefMainUrl)
-        if pyBrowser:
-            # Browser may be empty.
-            clientCallback = pyBrowser.GetClientCallback("GetCookieManager")
+        clientCallback = pyBrowser.GetClientCallback("GetCookieManager")
         if clientCallback:
             returnValue = clientCallback(
                     browser=pyBrowser,