Android: Add common function for adding/releasing native reference

webrtc/sdk/android/api/org/webrtc/RtpSender.java

Index: webrtc/sdk/android/api/org/webrtc/RtpSender.java
diff --git a/webrtc/sdk/android/api/org/webrtc/RtpSender.java b/webrtc/sdk/android/api/org/webrtc/RtpSender.java
index 29779532d4de04eb2f5c52ca62219420c14c0b78..fbb62db853c3cbe9e0f15b125cddbdbf9d9c4165 100644
--- a/webrtc/sdk/android/api/org/webrtc/RtpSender.java
+++ b/webrtc/sdk/android/api/org/webrtc/RtpSender.java
@@ -82,7 +82,7 @@ public class RtpSender {
     if (cachedTrack != null && ownsTrack) {
       cachedTrack.dispose();
     }
-    free(nativeRtpSender);
+    JniCommon.nativeReleaseRef(nativeRtpSender);
   }
 
   private static native boolean nativeSetTrack(long nativeRtpSender, long nativeTrack);
@@ -100,6 +100,4 @@ public class RtpSender {
   private static native RtpParameters nativeGetParameters(long nativeRtpSender);
 
   private static native String nativeId(long nativeRtpSender);
-
-  private static native void free(long nativeRtpSender);
 };