Introduce HttpDecoder::DecodeSettings(). In IETF QUIC, the client will cache a serialized SETTINGS frame (done in QuicSpdyClientSessionBase::OnSettingsFrame). Later when 0-rtt is attempted, the client session needs to decode the settings and apply to itself. Unused code. not protected. PiperOrigin-RevId: 310039639 Change-Id: I634670c019286ebe24e20f86b44da5a834e82066