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/soloader/FileLocker.java

@@ -0,0 +1,48 @@
+/**
+ * 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.soloader;
+import java.io.FileOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.nio.channels.FileLock;
+import java.io.Closeable;
+
+public final class FileLocker implements Closeable {
+
+  private final FileOutputStream mLockFileOutputStream;
+  private final FileLock mLock;
+
+  public static FileLocker lock(File lockFile) throws IOException {
+    return new FileLocker(lockFile);
+  }
+
+  private FileLocker(File lockFile) throws IOException {
+    mLockFileOutputStream = new FileOutputStream(lockFile);
+    FileLock lock = null;
+    try {
+      lock = mLockFileOutputStream.getChannel().lock();
+    } finally {
+      if (lock == null) {
+        mLockFileOutputStream.close();
+      }
+    }
+
+    mLock = lock;
+  }
+
+  @Override
+  public void close() throws IOException {
+    try {
+      mLock.release();
+    } finally {
+      mLockFileOutputStream.close();
+    }
+  }
+}