Disable flaky test WebRtcSessionTest.TestRtxRemovedByCreateAnswer on Win and Mac.

talk/app/webrtc/webrtcsession_unittest.cc

Index: talk/app/webrtc/webrtcsession_unittest.cc
diff --git a/talk/app/webrtc/webrtcsession_unittest.cc b/talk/app/webrtc/webrtcsession_unittest.cc
index 83659f09fe6d820bc20a6c34468b8b64d3aa4212..e76df06af78804fc87091587fa3dc98907312f62 100644
--- a/talk/app/webrtc/webrtcsession_unittest.cc
+++ b/talk/app/webrtc/webrtcsession_unittest.cc
@@ -4190,9 +4190,16 @@ TEST_P(WebRtcSessionTest, TestRenegotiateNewMediaWithCandidatesSeparated) {
   answer = CreateAnswer(NULL);
   SetLocalDescriptionWithoutError(answer);
 }
+
+// Flaky on Win and Mac only. See webrtc:4943
+#if defined(WEBRTC_WIN) || defined(WEBRTC_MAC)
+#define MAYBE_TestRtxRemovedByCreateAnswer DISABLED_TestRtxRemovedByCreateAnswer
+#else
+#define MAYBE_TestRtxRemovedByCreateAnswer TestRtxRemovedByCreateAnswer
+#endif
 // Tests that RTX codec is removed from the answer when it isn't supported
 // by local side.
-TEST_F(WebRtcSessionTest, TestRtxRemovedByCreateAnswer) {
+TEST_F(WebRtcSessionTest, MAYBE_TestRtxRemovedByCreateAnswer) {
   Init();
   SendAudioVideoStream1();
   std::string offer_sdp(kSdpWithRtx);