GitLab

Expand OAuth2ApiCallFlow class to allow multiple lines of headers & customizable expected http response code

BUG=1154032

Change-Id: Ia92533a9e8d0fa08d1156940d232314633057f08
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2577004
Commit-Queue: Alice Gong <alicego@google.com>
Reviewed-by: Alex Ilin <alexilin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834344}