Remove dead code from webrtc/base/timing.*

BUG=

Review URL: https://codereview.webrtc.org/1626253002

Cr-Original-Commit-Position: refs/heads/master@{#11366}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 7d0d0e0763fba5bf54d18b5dbb74dd65fdb63224
2 files changed