headless: Add a test for sending cookies from a protocol handler

This patch adds a test for sending outgoing cookies from a protocol
handler. The cookies are read asynchronously from the cookie store
associated with the request.

BUG=546953

Review-Url: https://codereview.chromium.org/2202053007
Cr-Commit-Position: refs/heads/master@{#409490}
1 file changed