Copy fbjni library from react-native

lib/fb/include/jni/Countable.h

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+#include <jni.h>
+
+#include <fb/Countable.h>
+#include <fb/RefPtr.h>
+#include <fb/visibility.h>
+
+namespace facebook {
+namespace jni {
+
+FBEXPORT const RefPtr<Countable>& countableFromJava(JNIEnv* env, jobject obj);
+
+template <typename T> RefPtr<T> extractRefPtr(JNIEnv* env, jobject obj) {
+  return static_cast<RefPtr<T>>(countableFromJava(env, obj));
+}
+
+template <typename T> RefPtr<T> extractPossiblyNullRefPtr(JNIEnv* env, jobject obj) {
+  return obj ? extractRefPtr<T>(env, obj) : nullptr;
+}
+
+FBEXPORT void setCountableForJava(JNIEnv* env, jobject obj, RefPtr<Countable>&& countable);
+
+void CountableOnLoad(JNIEnv* env);
+
+} }
+