Simplify ContentVerifierIOData, make it non ref-counted.

ContentVerifier always accesses its instance from IO thread, except
creation.

Bug: None
Test: No visible changes expected, cleanup.
Change-Id: Ie66773aec150a707fdc0c3e9325d903d23ab7138
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1682312
Commit-Queue: Istiaque Ahmed <[email protected]>
Reviewed-by: Devlin <[email protected]>
Cr-Commit-Position: refs/heads/master@{#674267}
3 files changed