Delete Timing class, timing.h, and update all users.

BUG=webrtc:6324

Review-Url: https://codereview.webrtc.org/2290203002
Cr-Original-Commit-Position: refs/heads/master@{#14203}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: cdf37a929336e2ca1e0bcdd5e858ffc75b2b317e
14 files changed