Remove deprecated PeerConnectionObserver::OnStateChange and OnIceComplete
Remove deprecated PeerConnectionObserver::OnStateChange and OnIceComplete

These methods are no longer used.
OnStateChange needs to be removed from Chrome before this cl lands. https://codereview.chromium.org/1668413003/

TBR=glaznev@webrtc.org for webrtc/examples

Review URL: https://codereview.webrtc.org/1669993003

Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#11537}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: dfb769d848e08ad4b15e94da502bbc2d99072d1d

jchavanton/webrtc,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,jchavanton/webrtc,jchavanton/webrtc,jchavanton/webrtc,Alkalyne/webrtctrunk,jchavanton/webrtc,jchavanton/webrtc,jchavanton/webrtc,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk