Don't treat picture ids as wrapping in the FrameBuffer2 class.

Picture ids are now unwrapped in the RtpFrameReferenceFinder class, so the
FrameBuffer2 no longer need to treat them as wrapping.

BUG=webrtc:7874

Review-Url: https://codereview.webrtc.org/3012883002
Cr-Original-Commit-Position: refs/heads/master@{#19779}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 3b3c9c4eb03cb82373a978eb9c5b8c8c08cc7e27
4 files changed