Disable check for all sent SSRCs being valid.
Disable check for all sent SSRCs being valid.

Since the code for setting these up will set the codec before setting
SSRCs for the streams, any frames sent in between will be sent on
random-generated SSRCs.

This part should be added back during work on issue 1695.

BUG=1695
R=stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/4629004

Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: e1fc3f22ea0d2f2b66e0ff65c175aa22bdb502d7

sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc