David Fifield authored Dec 20, 2018 and Georg Koppen committed Dec 20, 2018

This is supposed to remove and reset modified or unversioned files. This
ought to work around the problem with versioning of src/testing/gmock
and src/testing/gtest across upgrades.

$ gclient help sync
  -f, --force      force update even for unchanged modules
  -D, --delete_unversioned_trees
                   Deletes from the working copy any dependencies that
                   have been removed since the last sync, as long as
                   there are no local modifications. When used with
                   --force, such dependencies are removed even if they
                   have local modifications. When used with --reset, all
                   untracked directories are removed from the working
                   copy, excluding those which are explicitly ignored in
                   the repository.
  -R, --reset      resets any local changes before updating (git only)