[GN] Allow Xcode source indexing of non default files.

BUG=

Review-Url: https://codereview.chromium.org/2086463002
Cr-Original-Commit-Position: refs/heads/master@{#400919}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 7b90a1de5ac82360dcffce82744d6de866cb73ba
1 file changed
tree: fb7ffcfd887cc5ddbade6b33f3d16f491cbd9360
  1. tools/