Make |rtcp_send_transport| mandatory in FlexfecReceiveStream::Config.

webrtc/video/end_to_end_tests.cc

Index: webrtc/video/end_to_end_tests.cc
diff --git a/webrtc/video/end_to_end_tests.cc b/webrtc/video/end_to_end_tests.cc
index b7ae199de0651dab7ed8a8f9c0ecb36305f5e0f8..2c71e3951785cee43b0b5faa0165afd5c90d59d2 100644
--- a/webrtc/video/end_to_end_tests.cc
+++ b/webrtc/video/end_to_end_tests.cc
@@ -3888,7 +3888,8 @@ TEST_P(EndToEndTest, VerifyDefaultVideoReceiveConfigParameters) {
 }
 
 TEST_P(EndToEndTest, VerifyDefaultFlexfecReceiveConfigParameters) {
-  FlexfecReceiveStream::Config default_receive_config;
+  test::NullTransport rtcp_send_transport;
+  FlexfecReceiveStream::Config default_receive_config(&rtcp_send_transport);
   EXPECT_EQ(-1, default_receive_config.payload_type)
       << "Enabling FlexFEC requires rtpmap: flexfec negotiation.";
   EXPECT_EQ(0U, default_receive_config.remote_ssrc)