SAMLResponse only after inspecting (CTRL + SHIFT + I)

Hello, 
this piece of code:
```            
if req.url == 'https://signin.aws.amazon.com/saml':
self.saml_response = parse_qs(req.postData)['SAMLResponse'][0]
```
is working only, when in no headless mode I click right mouse button on the page and then choose inspect option.
Is there any way to make it automate?
