Upgrade fbjni

Summary:
Upgrades Yoga’s copy of *fbjni* to the latest version.

This will enable us

- to move from `finalize()` to `PhantomReference` to deallocate native memory, with the potential of making GC more efficient.
- to remove the internal dependency to *libfb,* allowing apps without an own dependency to ship less code

Reviewed By: passy

Differential Revision: D16220924

fbshipit-source-id: e8233fe2b5403946ff51f43cb6def558ded52fda

lib/fb/src/main/cpp/include/fbjni/NativeRunnable.h

@@ -0,0 +1,42 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the LICENSE
+ * file in the root directory of this source tree.
+ */
+#pragma once
+
+#include <fbjni/fbjni.h>
+
+#include <functional>
+
+namespace facebook {
+namespace jni {
+
+struct JRunnable : public JavaClass<JRunnable> {
+  static auto constexpr kJavaDescriptor = "Ljava/lang/Runnable;";
+};
+
+struct JNativeRunnable : public HybridClass<JNativeRunnable, JRunnable> {
+ public:
+  static auto constexpr kJavaDescriptor = "Lcom/facebook/jni/NativeRunnable;";
+
+  JNativeRunnable(std::function<void()>&& runnable) : runnable_(std::move(runnable)) {}
+
+  static void OnLoad() {
+    registerHybrid({
+        makeNativeMethod("run", JNativeRunnable::run),
+      });
+  }
+
+  void run() {
+    runnable_();
+  }
+
+ private:
+  std::function<void()> runnable_;
+};
+
+
+} // namespace jni
+} // namespace facebook