Only generate one CNAME per PeerConnection.

webrtc/api/peerconnectioninterface_unittest.cc

Index: webrtc/api/peerconnectioninterface_unittest.cc
diff --git a/webrtc/api/peerconnectioninterface_unittest.cc b/webrtc/api/peerconnectioninterface_unittest.cc
index 1a8dd57f08a6565f883c8ba5e73d69996fa1d623..2594b6c10637996c3a554757a188da633d5b12cb 100644
--- a/webrtc/api/peerconnectioninterface_unittest.cc
+++ b/webrtc/api/peerconnectioninterface_unittest.cc
@@ -934,6 +934,34 @@ class PeerConnectionInterfaceTest : public testing::Test {
     ASSERT_TRUE(stream->AddTrack(video_track));
   }
 
+  rtc::scoped_ptr<SessionDescriptionInterface> CreateOfferWithOneAudioStream() {
+    CreatePeerConnection();
+    AddVoiceStream(kStreamLabel1);
+    rtc::scoped_ptr<SessionDescriptionInterface> offer;
+    EXPECT_TRUE(DoCreateOffer(&offer, nullptr));
+    return offer;
+  }
+
+  rtc::scoped_ptr<SessionDescriptionInterface>
+  CreateAnswerWithOneAudioStream() {
+    rtc::scoped_ptr<SessionDescriptionInterface> offer =
+        CreateOfferWithOneAudioStream();
+    EXPECT_TRUE(DoSetRemoteDescription(offer.release()));
+    rtc::scoped_ptr<SessionDescriptionInterface> answer;
+    EXPECT_TRUE(DoCreateAnswer(&answer, nullptr));
+    return answer;
+  }
+
+  const std::string& GetFirstAudioStreamCname(
+      const SessionDescriptionInterface* desc) {
+    const cricket::ContentInfo* audio_content =
+        cricket::GetFirstAudioContent(desc->description());
+    const cricket::AudioContentDescription* audio_desc =
+        static_cast<const cricket::AudioContentDescription*>(
+            audio_content->description);
+    return audio_desc->streams()[0].cname;
+  }
+
   cricket::FakePortAllocator* port_allocator_ = nullptr;
   scoped_refptr<webrtc::PeerConnectionFactoryInterface> pc_factory_;
   scoped_refptr<PeerConnectionInterface> pc_;
@@ -941,6 +969,27 @@ class PeerConnectionInterfaceTest : public testing::Test {
   rtc::scoped_refptr<StreamCollection> reference_collection_;
 };
 
+// Generate different CNAMEs when PeerConnections are created.
+// The CNAMEs are expected to be generated randomly. It is possible
+// that the test fails, though the possibility is very low.
+TEST_F(PeerConnectionInterfaceTest, CnameGenerationInOffer) {
+  rtc::scoped_ptr<SessionDescriptionInterface> offer1 =
+      CreateOfferWithOneAudioStream();
+  rtc::scoped_ptr<SessionDescriptionInterface> offer2 =
+      CreateOfferWithOneAudioStream();
+  EXPECT_NE(GetFirstAudioStreamCname(offer1.get()),
+            GetFirstAudioStreamCname(offer2.get()));
+}
+
+TEST_F(PeerConnectionInterfaceTest, CnameGenerationInAnswer) {
+  rtc::scoped_ptr<SessionDescriptionInterface> answer1 =
+      CreateAnswerWithOneAudioStream();
+  rtc::scoped_ptr<SessionDescriptionInterface> answer2 =
+      CreateAnswerWithOneAudioStream();
+  EXPECT_NE(GetFirstAudioStreamCname(answer1.get()),
+            GetFirstAudioStreamCname(answer2.get()));
+}
+
 TEST_F(PeerConnectionInterfaceTest,
        CreatePeerConnectionWithDifferentConfigurations) {
   CreatePeerConnectionWithDifferentConfigurations();