Add an example app for Android native API.

The app is a simple loopback demo demonstrating the usage of Android
native API. This is an initial version and I will add support for
HW codecs etc. in the future.

Bug: webrtc:8769
Change-Id: Ifb6209769dabeb8ca3185b969a1ef8afd6d84390
Reviewed-on: https://webrtc-review.googlesource.com/60540
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Commit-Queue: Sami Kalliomäki <sakal@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22385}

examples/androidnativeapi/jni/androidcallclient.h

@@ -0,0 +1,73 @@
+/*
+ *  Copyright 2018 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.
+ */
+
+#ifndef EXAMPLES_ANDROIDNATIVEAPI_JNI_ANDROIDCALLCLIENT_H_
+#define EXAMPLES_ANDROIDNATIVEAPI_JNI_ANDROIDCALLCLIENT_H_
+
+#include <jni.h>
+
+#include <memory>
+#include <string>
+
+#include "api/peerconnectioninterface.h"
+#include "rtc_base/criticalsection.h"
+#include "rtc_base/scoped_ref_ptr.h"
+#include "rtc_base/thread_checker.h"
+#include "sdk/android/native_api/jni/scoped_java_ref.h"
+
+namespace webrtc_examples {
+
+class AndroidCallClient {
+ public:
+  AndroidCallClient();
+
+  void Call(JNIEnv* env,
+            const webrtc::JavaRef<jobject>& cls,
+            const webrtc::JavaRef<jobject>& local_sink,
+            const webrtc::JavaRef<jobject>& remote_sink);
+  void Hangup(JNIEnv* env, const webrtc::JavaRef<jobject>& cls);
+  // A helper method for Java code to delete this object. Calls delete this.
+  void Delete(JNIEnv* env, const webrtc::JavaRef<jobject>& cls);
+
+ private:
+  class PCObserver;
+
+  void CreatePeerConnectionFactory() RTC_RUN_ON(thread_checker_);
+  void CreatePeerConnection() RTC_RUN_ON(thread_checker_);
+  void Connect() RTC_RUN_ON(thread_checker_);
+
+  rtc::ThreadChecker thread_checker_;
+
+  bool call_started_ RTC_GUARDED_BY(thread_checker_);
+
+  const std::unique_ptr<PCObserver> pc_observer_;
+
+  rtc::scoped_refptr<webrtc::PeerConnectionFactoryInterface> pcf_
+      RTC_GUARDED_BY(thread_checker_);
+  std::unique_ptr<rtc::Thread> network_thread_ RTC_GUARDED_BY(thread_checker_);
+  std::unique_ptr<rtc::Thread> worker_thread_ RTC_GUARDED_BY(thread_checker_);
+  std::unique_ptr<rtc::Thread> signaling_thread_
+      RTC_GUARDED_BY(thread_checker_);
+
+  std::unique_ptr<rtc::VideoSinkInterface<webrtc::VideoFrame>> local_sink_
+      RTC_GUARDED_BY(thread_checker_);
+  std::unique_ptr<rtc::VideoSinkInterface<webrtc::VideoFrame>> remote_sink_
+      RTC_GUARDED_BY(thread_checker_);
+  rtc::scoped_refptr<webrtc::VideoTrackSourceInterface> video_source_
+      RTC_GUARDED_BY(thread_checker_);
+
+  rtc::CriticalSection pc_mutex_;
+  rtc::scoped_refptr<webrtc::PeerConnectionInterface> pc_
+      RTC_GUARDED_BY(pc_mutex_);
+};
+
+}  // namespace webrtc_examples
+
+#endif  // EXAMPLES_ANDROIDNATIVEAPI_JNI_ANDROIDCALLCLIENT_H_