Android: Add common function for adding/releasing native reference

webrtc/sdk/android/src/jni/pc/mediastreamtrack_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.
  */
 
 #include "webrtc/api/mediastreaminterface.h"
 #include "webrtc/sdk/android/src/jni/jni_helpers.h"
 
 namespace webrtc_jni {
 
-JNI_FUNCTION_DECLARATION(void,
-                         MediaStreamTrack_free,
-                         JNIEnv*,
-                         jclass,
-                         jlong j_p) {
-  reinterpret_cast<webrtc::MediaStreamTrackInterface*>(j_p)->Release();
-}
-
 JNI_FUNCTION_DECLARATION(jstring,
                          MediaStreamTrack_nativeId,
                          JNIEnv* jni,
                          jclass,
                          jlong j_p) {
   return JavaStringFromStdString(
       jni, reinterpret_cast<webrtc::MediaStreamTrackInterface*>(j_p)->id());
 }
 
 JNI_FUNCTION_DECLARATION(jstring,
@@ skipping 27 matching lines @@
                          MediaStreamTrack_nativeSetEnabled,
                          JNIEnv* jni,
                          jclass,
                          jlong j_p,
                          jboolean enabled) {
   return reinterpret_cast<webrtc::MediaStreamTrackInterface*>(j_p)->set_enabled(
       enabled);
 }
 
 }  // namespace webrtc_jni