Android: Add common function for adding/releasing native reference

webrtc/sdk/android/src/jni/wrapped_native_i420_buffer.cc

 /*
  *  Copyright (c) 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 28 matching lines @@
   jobject j_wrapped_native_i420_buffer = jni->NewObject(
       j_wrapped_native_i420_buffer_class, j_wrapped_native_i420_buffer_ctor_id,
       i420_buffer->width(), i420_buffer->height(), y_buffer,
       i420_buffer->StrideY(), u_buffer, i420_buffer->StrideU(), v_buffer,
       i420_buffer->StrideV(), jlongFromPointer(i420_buffer.get()));
   CHECK_EXCEPTION(jni);
 
   return j_wrapped_native_i420_buffer;
 }
 
-JNI_FUNCTION_DECLARATION(void,
-                         WrappedNativeI420Buffer_nativeAddRef,
-                         JNIEnv* jni,
-                         jclass,
-                         jlong j_buffer_pointer) {
-  reinterpret_cast<webrtc::VideoFrameBuffer*>(j_buffer_pointer)->AddRef();
-}
-
-JNI_FUNCTION_DECLARATION(void,
-                         WrappedNativeI420Buffer_nativeRelease,
-                         JNIEnv* jni,
-                         jclass,
-                         jlong j_buffer_pointer) {
-  reinterpret_cast<webrtc::VideoFrameBuffer*>(j_buffer_pointer)->Release();
-}
-
 }  // namespace webrtc_jni