Remove all old suspension logic.

I'm also removing media_optimization_unittest.cc, since it only tested the
suspension logic and nothing else.

R=pbos@webrtc.org

Review URL: https://codereview.webrtc.org/2119503002 .

Cr-Original-Commit-Position: refs/heads/master@{#13355}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: e15032c750564936da897d869a34c42aeb6b3288
9 files changed