Android: Add common function for adding/releasing native reference

webrtc/sdk/android/src/jni/pc/rtpreceiver_jni.cc

Index: webrtc/sdk/android/src/jni/pc/rtpreceiver_jni.cc
diff --git a/webrtc/sdk/android/src/jni/pc/rtpreceiver_jni.cc b/webrtc/sdk/android/src/jni/pc/rtpreceiver_jni.cc
index 26148a8e20746ba5bf75e53401428ec5e65f8436..92bc2ab318a8b1a861c6037abb5bfda9d4bed78c 100644
--- a/webrtc/sdk/android/src/jni/pc/rtpreceiver_jni.cc
+++ b/webrtc/sdk/android/src/jni/pc/rtpreceiver_jni.cc
@@ -50,12 +50,6 @@ JOW(jstring, RtpReceiver_nativeId)
           ->id());
 }
 
-JOW(void, RtpReceiver_free)
-(JNIEnv* jni, jclass, jlong j_rtp_receiver_pointer) {
-  reinterpret_cast<webrtc::RtpReceiverInterface*>(j_rtp_receiver_pointer)
-      ->Release();
-}
-
 JOW(jlong, RtpReceiver_nativeSetObserver)
 (JNIEnv* jni, jclass, jlong j_rtp_receiver_pointer, jobject j_observer) {
   RtpReceiverObserverJni* rtpReceiverObserver =