Remove OwnPtr::release() calls in platform/ (part inspector).

OwnPtr::release() calls can be (1) replaced with std::move(), or
(2) removed entirely (in certain "return" statements).

BUG=611660

Review-Url: https://codereview.chromium.org/1979963002
Cr-Commit-Position: refs/heads/master@{#394341}
18 files changed