Android: Add common function for adding/releasing native reference

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

 /*
  *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 32 matching lines @@
 }
 
 JOW(jstring, RtpReceiver_nativeId)
 (JNIEnv* jni, jclass, jlong j_rtp_receiver_pointer) {
   return JavaStringFromStdString(
       jni,
       reinterpret_cast<webrtc::RtpReceiverInterface*>(j_rtp_receiver_pointer)
           ->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 =
       new RtpReceiverObserverJni(jni, j_observer);
   reinterpret_cast<webrtc::RtpReceiverInterface*>(j_rtp_receiver_pointer)
       ->SetObserver(rtpReceiverObserver);
   return jlongFromPointer(rtpReceiverObserver);
 }
 
 JOW(void, RtpReceiver_nativeUnsetObserver)
 (JNIEnv* jni, jclass, jlong j_rtp_receiver_pointer, jlong j_observer_pointer) {
   reinterpret_cast<webrtc::RtpReceiverInterface*>(j_rtp_receiver_pointer)
       ->SetObserver(nullptr);
   RtpReceiverObserverJni* observer =
       reinterpret_cast<RtpReceiverObserverJni*>(j_observer_pointer);
   if (observer) {
     delete observer;
   }
 }
 
 }  // namespace webrtc_jni