Allow passing in a custom native library loader.

All previous initialize methods are deprecated and a new initialize
that uses a builder pattern is added. This gives us full control over
the order of initialization.

Bug: webrtc:7474
Change-Id: I006190e50f2e75c5015f0be75b86d367676db2cc
Reviewed-on: https://webrtc-review.googlesource.com/4160
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Commit-Queue: Sami Kalliomäki <sakal@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20037}

sdk/android/api/org/webrtc/NativeLibraryLoader.java

@@ -0,0 +1,24 @@
+/*
+ *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+package org.webrtc;
+
+/**
+ * Interface for loading native libraries. A custom loader can be passed to
+ * PeerConnectionFactory.initialize.
+ */
+public interface NativeLibraryLoader {
+  /**
+   * Loads a native library with the given name.
+   *
+   * @return True on success
+   */
+  boolean load(String name);
+}