GN docs: update the example of declare_args().

BUG=None

Review-Url: https://codereview.chromium.org/2714643005
Cr-Original-Commit-Position: refs/heads/master@{#452640}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: b7fb5fc4195bd36c81225691ae236363c1d05873
2 files changed
tree: 1219ad75813c5d51c53b2a3f5f5ce0248190bf1c
  1. tools/