Handle padded audio packets correctly

webrtc/modules/audio_coding/acm2/audio_coding_module.cc

Index: webrtc/modules/audio_coding/acm2/audio_coding_module.cc
diff --git a/webrtc/modules/audio_coding/acm2/audio_coding_module.cc b/webrtc/modules/audio_coding/acm2/audio_coding_module.cc
index e22eb5a5914cc4d5ba565659dc4e205eda41672d..252732a331d84e5b91752a1b4adf68bd8b002cfe 100644
--- a/webrtc/modules/audio_coding/acm2/audio_coding_module.cc
+++ b/webrtc/modules/audio_coding/acm2/audio_coding_module.cc
@@ -1079,6 +1079,11 @@ rtc::Optional<SdpAudioFormat> AudioCodingModuleImpl::ReceiveFormat() const {
 int AudioCodingModuleImpl::IncomingPacket(const uint8_t* incoming_payload,

[minyue-webrtc, 2017/05/09 21:04:06]

will this affect DTX sync packets?

[hlundin-webrtc, 2017/05/10 08:57:23]

Aren't they 1 or 2 bytes? 
https://cs.chromium.org/chromium/src/third_party/webrtc/modules/audio_coding/...

[minyue-webrtc, 2017/05/10 09:44:12]

Yes. Thanks

                                           const size_t payload_length,
                                           const WebRtcRTPHeader& rtp_header) {
+  if (payload_length == 0) {
+    // This is an empty packet, which is not a problem, but we will have to
+    // construct an empty ArrayView.
+    return receiver_.InsertPacket(rtp_header, rtc::ArrayView<const uint8_t>());
+  }
   return receiver_.InsertPacket(
       rtp_header,

[minyue-webrtc, 2017/05/09 21:04:06]

reading rtc::ArrayView i think it is safe to just use 1087-1089

[hlundin-webrtc, 2017/05/10 08:57:23]

I don't think so. If we construct an ArrayView with a non-null data pointer, but
a size==0, we will use the ctor at
https://cs.chromium.org/chromium/src/third_party/webrtc/base/array_view.h?typ....
This has a DCHECK at line 149, which says that if size==0, the data must be
nullptr.

[minyue-webrtc, 2017/05/10 09:44:11]

But shouldn't incoming_payload be a null?

[hlundin-webrtc, 2017/05/10 11:19:30]

Done.

       rtc::ArrayView<const uint8_t>(incoming_payload, payload_length));