Add some missing std::move()s following a previous refactoring

This patch adds some std::move() calls as a follow-up to
https://codereview.chromium.org/1730533002/. No functional changes.

BUG=546953
TBR=rsleevi@chromium.org

Review URL: https://codereview.chromium.org/1736273002

Cr-Commit-Position: refs/heads/master@{#377898}
3 files changed