Add support for async bridged methods to android

Differential Revision: D2595414

fb-gh-sync-id: 3b44ce1737bdd1e0861a285a45976631a57ab3b5

ReactAndroid/src/main/java/com/facebook/react/bridge/Promise.java

@@ -0,0 +1,22 @@
+/**
+ * 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.
+ */
+
+package com.facebook.react.bridge;
+
+/**
+ * Interface that represents a JavaScript Promise which can be passed to the native module as a
+ * method parameter.
+ *
+ * Methods annotated with {@link ReactMethod} that use {@link Promise} as type of the last parameter
+ * will be marked as "remoteAsync" and will return a promise when invoked from JavaScript.
+ */
+public interface Promise {
+  void resolve(Object value);
+  void reject(String reason);
+}