Fix warnings about implicit int to bool conversion and noexcept.

TEST=build on MVSV 2015

Change-Id: I437977ca01f62ce2df39872da5903a0338a73bba
Reviewed-on: https://chromium-review.googlesource.com/765371
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>