Update GN roller for new JSON endpoints.

Also, improve the error handling to exit cleanly and quickly with error messages
when necessary.

R=hinoka@chromium.org

Review-Url: https://codereview.chromium.org/2819853003
Cr-Original-Commit-Position: refs/heads/master@{#465414}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 53ca11c0fe7bbceeb9af4550c325e22201cbfc06
1 file changed
tree: f412d7407144be3e07d2503e67e1bb3c26c0a89d
  1. tools/