Reset speech encoder before hooking it up to RED or CNG

Commit 7e0c7d49 ("Add support for external encoders in ACM") changed
things around so that we no longer recreate the speech encoder when
adding CNG or RED to an existing encoder. This isn't correct, since
those two expect to be in sync with the speech encoder they work with.
Solve the problem by resetting the speech encoder before hooking in
RED or CNG.

BUG=crbug/490368
R=jmarusic@webrtc.org
TBR=henrik.lundin@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/53589004

Cr-Commit-Position: refs/heads/master@{#9307}
1 file changed