GitLab

Make it clear that Revoke() must be called after Consume(), which is
what the current DCEHCK in dtor checks. If an extension does not need to
be revoked, use ConsumePermanently().

BUG=510604
TEST=No functionality change

Change-Id: Ifee995ffdfc608e4ccc40bbbb4096511c561237a
Reviewed-on: https://chromium-review.googlesource.com/701274
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#506520}