DCHECK: Permit did_send_request & ENTRY_USED

In HttpCache::Transaction::RecordHistograms() it was asserted that the
CacheEntryStatus couldn't be ENTRY_USED when did_send_request was true.
It turns out that this is not always the case.

The DCHECK isn't protecting anything important, so permit this
combination of states.

BUG=1409150,1443598

Change-Id: I75aa10b07ccdb473072826c1b14cb18e7c33d1ac
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4550908


Reviewed-by: Kenichi Ishibashi <bashi@chromium.org>
Commit-Queue: Adam Rice <ricea@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1147620}