If true, the request is cancelled. This prevents the request from being
sent. This can be used as a response to the onBeforeRequest,
onBeforeSendHeaders, onHeadersReceived and onAuthRequired events.
Only used as a response to the onBeforeRequest and onHeadersReceived
events. If set, the original request is prevented from being
sent/completed and is instead redirected to the given URL. Redirections to
non-HTTP schemes such as data: are allowed. Redirects initiated by a
redirect action use the original request method for the redirect, with one
exception: If the redirect is initiated at the onHeadersReceived stage,
then the redirect will be issued using the GET method. Redirects from URLs
with ws:// and wss:// schemes are ignored.
Only used as a response to the onHeadersReceived event. If set, the server
is assumed to have responded with these response headers instead. Only
return responseHeaders if you really want to modify the headers in order
to limit the number of conflicts (only one extension may modify
responseHeaders for each request).
