[add] BackAndroid API stub

src/apis/BackAndroid/index.js

@@ -0,0 +1,28 @@
+/**
+ * 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.
+ *
+ * web stub for BackAndroid.android.js
+ *
+ * @providesModule BackAndroid
+ */
+
+'use strict';
+
+function emptyFunction() {}
+
+const BackAndroid = {
+  exitApp: emptyFunction,
+  addEventListener() {
+    return {
+      remove: emptyFunction
+    };
+  },
+  removeEventListener: emptyFunction
+};
+
+module.exports = BackAndroid;

src/index.js

@@ -9,6 +9,7 @@ import Animated from './apis/Animated';
 import AppRegistry from './apis/AppRegistry';
 import AppState from './apis/AppState';
 import AsyncStorage from './apis/AsyncStorage';
+import BackAndroid from './apis/BackAndroid';
 import Clipboard from './apis/Clipboard';
 import Dimensions from './apis/Dimensions';
 import Easing from 'animated/lib/Easing';
@@ -59,6 +60,7 @@ const ReactNative = {
   AppRegistry,
   AppState,
   AsyncStorage,
+  BackAndroid,
   Clipboard,
   Dimensions,
   Easing,