All audio in calls is now routed through AudioTransportProxy. The
AudioTransport implemented by VoEBaseImpl is disconnected from
AudioDevice and replaced by an empty proxy layer that forwards calls
to the old Transport. This is a refactoring CL in preparation for
landing https://codereview.webrtc.org/2436033002/, which will connect
the new AudioMixer.
In the planned configuration, the currently empty AudioTransportProxy
will query the new mixer for audio instead of polling data from the
old Transport. Mixed audio will be passed to an AudioProcessing
interface. AudioTransportProxy is initialized with an AudioProcessing*,
which is currently unused.
No presubmit since we implement an interface with non-const references.
NOPRESUBMIT=True
BUG=webrtc:6346
Review-Url: https://codereview.webrtc.org/2454373002
Cr-Commit-Position: refs/heads/master@{#15133}
