Add information on the requirements for a new Chromium port.

Review-Url: https://codereview.chromium.org/2909733002
Cr-Original-Commit-Position: refs/heads/master@{#475553}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 2928b5dc30a1978a743009533b0a25d49dd9ee46
1 file changed
tree: d657c8013857b2ff8bcfef659858ce00e784db36
  1. tools/