This reverts commit 5831afb8328cbecdbdbee882280ef907a09d9f31. Reason for revert: The code is still in use: https://ci.chromium.org/ui/p/webrtc/builders/ci/Win32%20Builder%20(Clang)/10243/overview. It wasn't detected for some reasons. Original change's description: > Delete unused class GlobalMutex > > Bug: webrtc:13869 > Change-Id: Id3655bdd24630b78e83b606291605a37129fd4bc > Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/258131 > Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> > Commit-Queue: Niels Moller <nisse@webrtc.org> > Cr-Commit-Position: refs/heads/main@{#36478} Bug: webrtc:13869 Change-Id: Id44dd4f8ec31ac9e05fc0ee75b55916e627fd7bf No-Presubmit: true No-Tree-Checks: true No-Try: true Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/258135 Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com> Owners-Override: Artem Titov <titovartem@webrtc.org> Commit-Queue: Artem Titov <titovartem@webrtc.org> Cr-Commit-Position: refs/heads/main@{#36480}