Recently every "gclient sync" creates a directory third_party/gles1_conform/ which shows up as untracked:

$ git status
HEAD detached at origin/master
Untracked files:
  (use "git add <file>..." to include in what will be committed)

	third_party/gles1_conform/

nothing added to commit but untracked files present (use "git add" to track)

I'm guessing it's related to this commit, although I don't understand DEPS well enough to say what's wrong with it:

  https://chrome-internal.googlesource.com/chrome/src-internal/+/2aef9c11251fd3a893b649b930549bb8461d9b1d