Replace use Clock::CurrentNtp with CurrentNtpTime

BUG=None

Review-Url: https://codereview.webrtc.org/2694713002
Cr-Original-Commit-Position: refs/heads/master@{#16721}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 4228784609afcea28174a673e4a2024b9a75c628
2 files changed