Verify parsed QP value when frame is encoded instead of storing parsed value and verifying later.

Removes:
- VideoProcessor: GetQpFromEncoder, GetQpFromBitstream
- FrameInfo: qp_encoder, qp_bitstream

BUG=webrtc:6634

Review-Url: https://codereview.webrtc.org/3007753002
Cr-Original-Commit-Position: refs/heads/master@{#19579}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: a16c70b8ba37b07b6fa82b2a4314f6f608ad079e
3 files changed