[Post Message] Remove old counters
These counters were designed just for post-message and with the idea of
there being easy parts to block. Since that didn't pan out and we not
want to add more detailed counters for not just post-message, but all
opener functions it would be better to remove this so we aren't logging
unneeded UKM.
Bug: 1159586
Change-Id: I98542c199f7fe8420d9dfa0d5eebb75589a76f9e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5683602
Auto-Submit: Ari Chivukula arichiv@chromium.org
Reviewed-by: Robert Flack flackr@chromium.org
Reviewed-by: Sun Yueru yrsun@chromium.org
Reviewed-by: Alexander Timin altimin@chromium.org
Reviewed-by: Daniel Cheng dcheng@chromium.org
Commit-Queue: Sun Yueru yrsun@chromium.org
Cr-Commit-Position: refs/heads/main@{#1324861}