Merge SignalPortPruned and SignalPortsRemoved.
These two signals have the same purpose and is kind of redundant.
Rename to SignalPortsPruned.

BUG=
R=pthatcher@webrtc.org, zhihuang@webrtc.org

Review URL: https://codereview.webrtc.org/2176743003 .

Cr-Original-Commit-Position: refs/heads/master@{#13562}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 8eeecabd3345c0f5bd86d7a32d0b57268179bebf
6 files changed