[gpu] Add put_offset to CommandBufferService::PutChanged trace events

Useful for debugging traces.

Bug: 40273077
Change-Id: I0df9bc3a2ea11d78fc1245c6519632106a6a6964
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7499039
Reviewed-by: Loko Kung <lokokung@google.com>
Auto-Submit: Sunny Sachanandani <sunnyps@chromium.org>
Commit-Queue: Sunny Sachanandani <sunnyps@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1571992}
NOKEYCHECK=True
GitOrigin-RevId: 9a028d1487f1a94ff7a0621aaaa0f47d1bfb6e41