Release React Native for Android

This is an early release and there are several things that are known
not to work if you're porting your iOS app to Android.

See the Known Issues guide on the website.

We will work with the community to reach platform parity with iOS.

ReactAndroid/src/main/java/com/facebook/react/modules/common/ModuleDataCleaner.java

@@ -0,0 +1,50 @@
+/**
+ * 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.modules.common;
+
+import com.facebook.common.logging.FLog;
+import com.facebook.react.bridge.CatalystInstance;
+import com.facebook.react.bridge.NativeModule;
+import com.facebook.react.common.ReactConstants;
+
+/**
+ * Cleans sensitive user data from native modules that implement the {@code Cleanable} interface.
+ * This is useful e.g. when a user logs out from an app.
+ */
+public class ModuleDataCleaner {
+
+  /**
+   * Indicates a module may contain sensitive user data and should be cleaned on logout.
+   *
+   * Types of data that should be cleaned:
+   * - Persistent data (disk) that may contain user information or content.
+   * - Retained (static) in-memory data that may contain user info or content.
+   *
+   * Note that the following types of modules do not need to be cleaned here:
+   * - Modules whose user data is kept in memory in non-static fields, assuming the app uses a
+   *   separate instance for each viewer context.
+   * - Modules that remove all persistent data (temp files, etc) when the catalyst instance is
+   *   destroyed. This is because logout implies that the instance is destroyed. Apps should enforce
+   *   this.
+   */
+  public interface Cleanable {
+
+    void clearSensitiveData();
+  }
+
+  public static void cleanDataFromModules(CatalystInstance catalystInstance) {
+    for (NativeModule nativeModule : catalystInstance.getNativeModules()) {
+      if (nativeModule instanceof Cleanable) {
+        FLog.d(ReactConstants.TAG, "Cleaning data from " + nativeModule.getName());
+        ((Cleanable) nativeModule).clearSensitiveData();
+      }
+    }
+  }
+}