Add support for customizing GN's args text.

It would be nice if, when you ran `gn args out/foo`, you could get
some sample text that was actually customized to the build that
you have, rather than referencing dummy arguments like 'enable_doom_melon'.

This CL adds support for that. If you set `arg_file_template_path` in
your dotfile, then GN will use the contents of that file as the sample
text that it passes to the editor.

R=brettw@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/2514333005
Cr-Original-Commit-Position: refs/heads/master@{#454750}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: eacf0f430d80615f07da8bc4094bb981771a155c
5 files changed
tree: 6abd6f3a45f326911fb33f85d9257a2085b00197
  1. tools/