Set local ssrc at construction of Rtp module

The SetSSRC() method is slated for removal, make sure we set the local
SSRC at construction time.

Bug: webrtc:10774
Change-Id: I431e828caf60c5e0134adbe82d1d3345745cc6ae
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/149827
Commit-Queue: Erik Språng <sprang@webrtc.org>
Reviewed-by: Fredrik Solenberg <solenberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28926}
diff --git a/audio/audio_send_stream_unittest.cc b/audio/audio_send_stream_unittest.cc
index 94bc34c..9f0504c 100644
--- a/audio/audio_send_stream_unittest.cc
+++ b/audio/audio_send_stream_unittest.cc
@@ -208,7 +208,7 @@
     EXPECT_CALL(*channel_send_, GetRtpRtcp()).WillRepeatedly(Invoke([this]() {
       return &this->rtp_rtcp_;
     }));
-    EXPECT_CALL(*channel_send_, SetLocalSSRC(kSsrc)).Times(1);
+    EXPECT_CALL(rtp_rtcp_, SSRC).WillRepeatedly(Return(kSsrc));
     EXPECT_CALL(*channel_send_, SetRTCP_CNAME(StrEq(kCName))).Times(1);
     EXPECT_CALL(*channel_send_, SetFrameEncryptor(_)).Times(1);
     EXPECT_CALL(*channel_send_, SetExtmapAllowMixed(false)).Times(1);