If a CNG packet is received first, followed by a speech packet with
another sample rate, NetEq should treat this as a change of codec, flush
out the CNG packet and reset the sample rate to that of the speech
packet.
BUG=webrtc:5447
NOTRY=True
Review-Url: https://codereview.webrtc.org/2307493002
Cr-Commit-Position: refs/heads/master@{#14032}