Refactor before implementing per stream suspension.

This CL contains a few minor changes to names, function signatures and
merges two structs into one.

BUG=5868

Review-Url: https://codereview.webrtc.org/1952923005
Cr-Original-Commit-Position: refs/heads/master@{#12716}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 2ebe5b1cd8e2e9b3142a122a56a1204904aad1d2
4 files changed