ios/third_party/gtx/README.chromium update Revision

This Revision has been derived using the provided version.

Revisions are now required for dependencies with a git upstream.

This is an initial attempt to uplift the current README metadata.

Respond with Code-Review '-1' if this README file is automatically
updated, you will need to update your automation.

If you need help, or it's not feasible,
file a bug similar to b/352221788 (android_deps).

FAQ:
* Google-internal: go/fix_chromium_metadata
* External: https://docs.google.com/document/d/1pejJ6JSS4lfDfnZ23VfpT1qJ1irDHMBueauCza6tNuo

This CL was uploaded by git cl split.

R=lindsayw@chromium.org

Bug: 350851535
Change-Id: I47b044735d389978fc3397c151a5224aa24220ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5715910


Reviewed-by: Jordan Brown <rop@google.com>
Commit-Queue: Jordan Brown <rop@google.com>
Reviewed-by: Lindsay Pasricha <lindsayw@chromium.org>
Auto-Submit: Jordan Brown <rop@google.com>
Cr-Commit-Position: refs/heads/main@{#1343869}