Add some more scoped_ptr functions in values.h

And convert some existing usage of bare pointer functions to their
scoped_ptr counterparts.

BUG=none

Review URL: https://codereview.chromium.org/1115423003

Cr-Commit-Position: refs/heads/master@{#328676}
12 files changed