ACM CodecOwner: Test that we reset speech encoder when enabling CNG or RED

If we don't, we'll end up crashing if they're enabled when the speech
encoder is in the middle of encoding a packet, since CNG and RED
assume that the speech encoder starts out with an empty buffer
(because they need to be in sync with it).

BUG=chromium:490368

Review URL: https://codereview.webrtc.org/1331853002

Cr-Commit-Position: refs/heads/master@{#9917}
1 file changed