Fix misspellings in GN reference

Change-Id: If752363b90772f07b70a16c369583b03948a05a7
Reviewed-on: https://chromium-review.googlesource.com/738094
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#533370}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: f7f761c756aff8bf4b993eb2dc37f934a5775f53