Use the same draft version in SDP data channel answers as used in the offer.

webrtc/pc/mediasession_unittest.cc

Index: webrtc/pc/mediasession_unittest.cc
diff --git a/webrtc/pc/mediasession_unittest.cc b/webrtc/pc/mediasession_unittest.cc
index 6676240b0c4e8b258e5098b1e996d4b5a1559ac9..2665e582c6b2147f9e5ba4056b6e0c101c35d21d 100644
--- a/webrtc/pc/mediasession_unittest.cc
+++ b/webrtc/pc/mediasession_unittest.cc
@@ -969,6 +969,46 @@ TEST_F(MediaSessionDescriptionFactoryTest, TestCreateDataAnswerGcm) {
   EXPECT_EQ(std::string(cricket::kMediaProtocolSavpf), vcd->protocol());
 }
 
+TEST_F(MediaSessionDescriptionFactoryTest, TestCreateDataAnswerUsesSctpmap) {

[Taylor Brandstetter, 2017/02/17 22:15:35]

Could you leave a comment above these two tests describing what they're testing
from a high level? For example, "Test that the use_sctpmap flag in an answer,
representing whether or not SDP will use legacy 'a=sctpmap' attributes, matches
the flag in the offer."

[Zach Stein, 2017/02/17 22:55:28]

Done.

+  MediaSessionOptions opts;
+  opts.data_channel_type = cricket::DCT_SCTP;
+  std::unique_ptr<SessionDescription> offer(f1_.CreateOffer(opts, NULL));

[Taylor Brandstetter, 2017/02/17 22:15:35]

We use C++11 "nullptr" instead of "NULL". Though don't worry about changing it
in this CL; I'm going to run a script to convert every "NULL" to "nullptr" some
time soon. https://codereview.webrtc.org/2685783014/

[Zach Stein, 2017/02/17 22:55:28]

I'll match the rest of the file for now.

+  ASSERT_TRUE(offer.get() != NULL);
+  ContentInfo* offer_dv = offer->GetContentByName("data");

[Taylor Brandstetter, 2017/02/17 22:15:35]

What does "dv" stand for?

I'd suggest more descriptive names, such as "offer_data_content",
"offer_data_description", though it matters less in a unit test.

[Zach Stein, 2017/02/17 22:55:28]

I meant for this to be dc for data content - I'll change it to that. This
matches the rest of the file. The test above uses vc instead of dc - I'll fix
that one too. I would rather not change the entire file here though, so I'll
stick with dc instead of data_content for now.

+  ASSERT_TRUE(offer_dv != NULL);
+  DataContentDescription* offer_dvd =
+      static_cast<DataContentDescription*>(offer_dv->description);
+  EXPECT_TRUE(offer_dvd->use_sctpmap());
+
+  std::unique_ptr<SessionDescription> answer(
+      f2_.CreateAnswer(offer.get(), opts, NULL));
+  const ContentInfo* answer_dv = answer->GetContentByName("data");
+  ASSERT_TRUE(answer_dv != NULL);
+  const DataContentDescription* answer_dvd =
+      static_cast<const DataContentDescription*>(answer_dv->description);
+  EXPECT_TRUE(answer_dvd->use_sctpmap());
+}
+
+TEST_F(MediaSessionDescriptionFactoryTest, TestCreateDataAnswerWithoutSctpmap) {
+  MediaSessionOptions opts;
+  opts.data_channel_type = cricket::DCT_SCTP;
+  std::unique_ptr<SessionDescription> offer(f1_.CreateOffer(opts, NULL));
+  ASSERT_TRUE(offer.get() != NULL);
+  ContentInfo* offer_dv = offer->GetContentByName("data");
+  ASSERT_TRUE(offer_dv != NULL);
+  DataContentDescription* offer_dvd =
+      static_cast<DataContentDescription*>(offer_dv->description);
+  offer_dvd->set_use_sctpmap(false);
+
+  std::unique_ptr<SessionDescription> answer(
+      f2_.CreateAnswer(offer.get(), opts, NULL));
+  const ContentInfo* answer_dv = answer->GetContentByName("data");
+  ASSERT_TRUE(answer_dv != NULL);
+  const DataContentDescription* answer_dvd =
+      static_cast<const DataContentDescription*>(answer_dv->description);
+  EXPECT_FALSE(answer_dvd->use_sctpmap());
+}
+
 // Verifies that the order of the media contents in the offer is preserved in
 // the answer.
 TEST_F(MediaSessionDescriptionFactoryTest, TestCreateAnswerContentOrder) {