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Most of the new issues are related to BackupRefPtr, but some
unrelated ones surfaced recently too. While at it, format the
CheckedPtr2/MTECheckedPtr better.

See this section for more details:
https://docs.google.com/document/d/1cnpd5Rwesq7DCZiD8FIJfPGHvQN3-Gul6xib_4hwfBg/edit?ts=5ed2d317#heading=h.jeb8au4vq4yf

Bug: 1069567
Change-Id: Ic49feaff08450ed4ac9ca93b03ef9d5b71245f28
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2437832Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Bartek Nowierski <bartekn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#811922}