RTPPayloadRegistry: Stop using the rate to keep track of receive codecs

webrtc/modules/rtp_rtcp/test/testAPI/test_api_audio.cc

Index: webrtc/modules/rtp_rtcp/test/testAPI/test_api_audio.cc
diff --git a/webrtc/modules/rtp_rtcp/test/testAPI/test_api_audio.cc b/webrtc/modules/rtp_rtcp/test/testAPI/test_api_audio.cc
index a88ffc81daa23f6f806a3f9b13b6f51da5f68da9..2801c65b907bbf0cedb2426f2741dcb9bb9f72a0 100644
--- a/webrtc/modules/rtp_rtcp/test/testAPI/test_api_audio.cc
+++ b/webrtc/modules/rtp_rtcp/test/testAPI/test_api_audio.cc
@@ -75,10 +75,7 @@ class RTPCallback : public NullRtpFeedback {
                               const int frequency,
                               const size_t channels,
                               const uint32_t rate) override {
-    if (payloadType == kPcmuPayloadType) {
-      EXPECT_EQ(kTestRate, rate) <<
-          "The rate should be 64K for this payloadType";
-    }
+    EXPECT_EQ(0u, rate) << "The rate should be zero";
     return 0;
   }
 };