Implemented the GetSources() in native code.

webrtc/api/test/mock_rtpreceiver.h

Index: webrtc/api/test/mock_rtpreceiver.h
diff --git a/webrtc/api/test/mock_rtpreceiver.h b/webrtc/api/test/mock_rtpreceiver.h
index 25f5c28caa62b3ac2c70121a750b5a0ca9a94cad..8033d5fd01764239b641c5118734acc78c2e1d81 100644
--- a/webrtc/api/test/mock_rtpreceiver.h
+++ b/webrtc/api/test/mock_rtpreceiver.h
@@ -11,7 +11,9 @@
 #ifndef WEBRTC_API_TEST_MOCK_RTPRECEIVER_H_
 #define WEBRTC_API_TEST_MOCK_RTPRECEIVER_H_
 
+#include <memory>

[the sun, 2017/04/05 14:58:29]

Needed why?

[Zhi Huang, 2017/04/06 03:09:49]

I missed this when removing the unique_ptrs.
Done.

 #include <string>
+#include <vector>
 
 #include "webrtc/api/rtpreceiverinterface.h"
 #include "webrtc/test/gmock.h"
@@ -27,6 +29,7 @@ class MockRtpReceiver : public rtc::RefCountedObject<RtpReceiverInterface> {
   MOCK_CONST_METHOD0(GetParameters, RtpParameters());
   MOCK_METHOD1(SetParameters, bool(const RtpParameters&));
   MOCK_METHOD1(SetObserver, void(RtpReceiverObserverInterface*));
+  MOCK_METHOD0(GetSources, std::vector<RtpSource>());
 };
 
 }  // namespace webrtc