Fixing bug where "mid" wasn't preserved across re-offers.

talk/session/media/mediasession_unittest.cc

 /*
  * libjingle
  * Copyright 2004 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  *  1. Redistributions of source code must retain the above copyright notice,
  *     this list of conditions and the following disclaimer.
  *  2. Redistributions in binary form must reproduce the above copyright notice,
@@ skipping 51 matching lines @@
 using cricket::StreamParams;
 using cricket::StreamParamsVec;
 using cricket::TransportDescription;
 using cricket::TransportDescriptionFactory;
 using cricket::TransportInfo;
 using cricket::ContentInfo;
 using cricket::CryptoParamsVec;
 using cricket::AudioContentDescription;
 using cricket::VideoContentDescription;
 using cricket::DataContentDescription;
+using cricket::GetFirstAudioContent;
+using cricket::GetFirstVideoContent;
+using cricket::GetFirstDataContent;
 using cricket::GetFirstAudioContentDescription;
 using cricket::GetFirstVideoContentDescription;
 using cricket::GetFirstDataContentDescription;
 using cricket::kAutoBandwidth;
 using cricket::AudioCodec;
 using cricket::VideoCodec;
 using cricket::DataCodec;
 using cricket::NS_JINGLE_RTP;
 using cricket::MEDIA_TYPE_AUDIO;
 using cricket::MEDIA_TYPE_VIDEO;
@@ skipping 518 matching lines @@
   EXPECT_TRUE(NULL != acd);
   EXPECT_TRUE(NULL != dcd);
 
   ASSERT_CRYPTO(acd, 1U, CS_AES_CM_128_HMAC_SHA1_80);
   EXPECT_EQ(std::string(cricket::kMediaProtocolSavpf), acd->protocol());
   ASSERT_CRYPTO(vcd, 1U, CS_AES_CM_128_HMAC_SHA1_80);
   EXPECT_EQ(std::string(cricket::kMediaProtocolSavpf), vcd->protocol());
   ASSERT_CRYPTO(dcd, 1U, CS_AES_CM_128_HMAC_SHA1_80);
   EXPECT_EQ(std::string(cricket::kMediaProtocolSavpf), dcd->protocol());
 }
+
 // Create a RTP data offer, and ensure it matches what we expect.
 TEST_F(MediaSessionDescriptionFactoryTest, TestCreateRtpDataOffer) {
   MediaSessionOptions opts;
   opts.data_channel_type = cricket::DCT_RTP;
   f1_.set_secure(SEC_ENABLED);
   rtc::scoped_ptr<SessionDescription>
       offer(f1_.CreateOffer(opts, NULL));
   ASSERT_TRUE(offer.get() != NULL);
   const ContentInfo* ac = offer->GetContentByName("audio");
   const ContentInfo* dc = offer->GetContentByName("data");
@@ skipping 1686 matching lines @@
   offer.reset(f1_.CreateOffer(options, NULL));
   ASSERT_TRUE(offer.get() != NULL);
   audio_content = offer->GetContentByName("audio");
   EXPECT_TRUE(VerifyNoCNCodecs(audio_content));
   rtc::scoped_ptr<SessionDescription> answer(
       f1_.CreateAnswer(offer.get(), options, NULL));
   ASSERT_TRUE(answer.get() != NULL);
   audio_content = answer->GetContentByName("audio");
   EXPECT_TRUE(VerifyNoCNCodecs(audio_content));
 }
+
+// Test that the content name ("mid" in SDP) is unchanged when creating a
+// new offer.
+TEST_F(MediaSessionDescriptionFactoryTest,
+       TestContentNameNotChangedInSubsequentOffers) {
+  MediaSessionOptions opts;
+  opts.recv_audio = true;
+  opts.recv_video = true;
+  opts.data_channel_type = cricket::DCT_SCTP;
+  // Create offer and modify the default content names.
+  rtc::scoped_ptr<SessionDescription> offer(f1_.CreateOffer(opts, nullptr));
+  for (ContentInfo& content : offer->contents()) {
+    content.name.append("_modified");
+  }
+
+  rtc::scoped_ptr<SessionDescription> updated_offer(
+      f1_.CreateOffer(opts, offer.get()));
+  const ContentInfo* audio_content = GetFirstAudioContent(updated_offer.get());
+  const ContentInfo* video_content = GetFirstVideoContent(updated_offer.get());
+  const ContentInfo* data_content = GetFirstDataContent(updated_offer.get());
+  ASSERT_TRUE(audio_content != nullptr);
+  ASSERT_TRUE(video_content != nullptr);
+  ASSERT_TRUE(data_content != nullptr);
+  EXPECT_EQ("audio_modified", audio_content->name);
+  EXPECT_EQ("video_modified", video_content->name);
+  EXPECT_EQ("data_modified", data_content->name);
+}