This fix will ensure that attempts to send DTMF
events before the channel is opened will return
a failure rather than disappearing the event.
Bug: webrtc:8908
Change-Id: I5044a0398dfd3dfe73b6ae1d48395e9809f81ad4
Reviewed-on: https://webrtc-review.googlesource.com/55480
Reviewed-by: Fredrik Solenberg <solenberg@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22121}