Trace encoding/decoding time in a generic way.

Removes VP8::Encode trace in favor of VCMGenericEncoder ones and adds
one to InitEncode. Also adds an instant event to ::Encoded since this
can be done on a different thread.

Also adds the corresponding traces to VCMGenericDecoder.

BUG=webrtc:5167
R=stefan@webrtc.org

Review URL: https://codereview.webrtc.org/1412573010

Cr-Original-Commit-Position: refs/heads/master@{#10674}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: d9eec762ce8bdc90bd18a387cacae8cab90440f1
3 files changed