Using AudioOption to enable audio network adaptor.

webrtc/audio/audio_send_stream.cc

Index: webrtc/audio/audio_send_stream.cc
diff --git a/webrtc/audio/audio_send_stream.cc b/webrtc/audio/audio_send_stream.cc
index fbed0f12af09281f57adc8620a3de708d1bb5a63..b321369ec1c17b34413532915423a395ac205f08 100644
--- a/webrtc/audio/audio_send_stream.cc
+++ b/webrtc/audio/audio_send_stream.cc
@@ -387,6 +387,24 @@ bool AudioSendStream::SetupSendCodec() {
         return false;
       }
     }
+
+    if (config_.audio_network_adaptor_config) {

[the sun, 2016/10/25 09:25:46]

Is the invariant that max/min_ptime_ms must be set when the config is specified?
DCHECK that here then.

What if max < min, etc? I can't make out what happens from the convoluted
structure below this level.

[minyue-webrtc, 2016/10/27 14:33:10]

They are parsed from SDP. This is checked down in Audio Network Adaptor which
DCHECKs that the initial sending frame length is covered in the range. It would
be good to check it in SDP parser too. But I found that pMinTime is not really
parsed there. see
https://cs.chromium.org/chromium/src/third_party/webrtc/api/webrtcsdp.cc?q=kC...

The consequence is that we will use default value and the maxptime, which is
parsed, needs to be meaningful. Therefore I added a DCHECK at the place where
the eventual values are determined.

BTW, maybe pmintime should be parsed (in a separate CL).

+      // Audio network adaptor is only allowed for Opus currently.
+      // |SetReceiverFrameLengthRange| needs to be called before
+      // |EnableAudioNetworkAdaptor|.
+      channel_proxy_->SetReceiverFrameLengthRange(send_codec_spec.min_ptime_ms,
+                                                  send_codec_spec.max_ptime_ms);
+      if (!channel_proxy_->EnableAudioNetworkAdaptor(
+              *config_.audio_network_adaptor_config)) {
+        LOG(LS_ERROR) << "Audio network adaptor cannot be enabled on SSRC "
+                      << config_.rtp.ssrc;
+        return false;
+      }
+      LOG(LS_INFO) << "Audio network adaptor enabled on SSRC "
+                   << config_.rtp.ssrc;
+    } else {
+      channel_proxy_->DisableAudioNetworkAdaptor();
+    }
   }
 
   // Set the CN payloadtype and the VAD status.