Replace the easy cases of VERIFY usage.

BUG=webrtc:6424

Review-Url: https://codereview.webrtc.org/2652653012
Cr-Original-Commit-Position: refs/heads/master@{#16370}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 7ce109acd37ff1981e6b65eb96500700513743a5
5 files changed