Fix chromium style checker error on windows sandbox code.

This change fixes "Complex constructor has an inline body."
error generated by Windows clang.

Original patch from yyanisawa@chromium.org, reviewed at
https://codereview.chromium.org/1252913006/

BUG=82385
TBR=wfh

Review URL: https://codereview.chromium.org/1257963003.

Cr-Commit-Position: refs/heads/master@{#340690}
5 files changed