Add Java support for AudioProcessing and PostProcessing injection

This allows injection of a user-defined post processing module from
the Android layer.

Bug: webrtc:8163
Change-Id: If3a6b4726c34c5f82d186b8cf95373c283cbd3f6
Reviewed-on: https://webrtc-review.googlesource.com/7610
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Commit-Queue: Sam Zackrisson <saza@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20367}

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

@@ -0,0 +1,20 @@
+/*
+ *  Copyright 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;
+
+/** Factory for creating webrtc::AudioProcessing instances. */
+public interface AudioProcessingFactory {
+  /**
+   * Dynamically allocates a webrtc::AudioProcessing instance and returns a pointer to it.
+   * The caller takes ownership of the object.
+   */
+  public long createNative();
+}