tree 9c0053619caf1da080e06478e7e0e11fc9db08b5
parent be874929c85852359c0e3f5e585e79ef797479ba
author dpranke <dpranke@chromium.org> 1475876688 -0700
committer Commit bot <commit-bot@chromium.org> 1475876812 +0000

Update GN documentation.

This CL updates the main GN page to reflect that the migration is
basically done, and also adds documentation for the magic
top-level "//:default" target (which we don't actually use in Chromium).

R=brettw@chromium.org, kjellander@chromium.org

Review-Url: https://codereview.chromium.org/2407523002
Cr-Original-Commit-Position: refs/heads/master@{#423973}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: e5e5a9dd1ca6b2d16db5ca08031ccade0654504f