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/java/org/webrtc/examples/androidnativeapi/CallClient.java

@@ -0,0 +1,56 @@
+/*
+ *  Copyright (c) 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.
+ */
+
+package org.webrtc.examples.androidnativeapi;
+
+import android.os.Handler;
+import android.os.HandlerThread;
+import org.webrtc.NativeClassQualifiedName;
+import org.webrtc.VideoSink;
+
+public class CallClient {
+  private static final String TAG = "CallClient";
+
+  private final HandlerThread thread;
+  private final Handler handler;
+
+  private long nativeClient;
+
+  public CallClient() {
+    thread = new HandlerThread(TAG + "Thread");
+    thread.start();
+    handler = new Handler(thread.getLooper());
+    handler.post(() -> { nativeClient = nativeCreateClient(); });
+  }
+
+  public void call(VideoSink localSink, VideoSink remoteSink) {
+    handler.post(() -> { nativeCall(nativeClient, localSink, remoteSink); });
+  }
+
+  public void hangup() {
+    handler.post(() -> { nativeHangup(nativeClient); });
+  }
+
+  public void close() {
+    handler.post(() -> {
+      nativeDelete(nativeClient);
+      nativeClient = 0;
+    });
+    thread.quitSafely();
+  }
+
+  private static native long nativeCreateClient();
+  @NativeClassQualifiedName("webrtc_examples::AndroidCallClient")
+  private static native void nativeCall(long nativePtr, VideoSink localSink, VideoSink remoteSink);
+  @NativeClassQualifiedName("webrtc_examples::AndroidCallClient")
+  private static native void nativeHangup(long nativePtr);
+  @NativeClassQualifiedName("webrtc_examples::AndroidCallClient")
+  private static native void nativeDelete(long nativePtr);
+}

examples/androidnativeapi/java/org/webrtc/examples/androidnativeapi/MainActivity.java

@@ -0,0 +1,80 @@
+/*
+ *  Copyright (c) 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.
+ */
+
+package org.webrtc.examples.androidnativeapi;
+
+import android.app.Activity;
+import android.os.Bundle;
+import android.widget.Button;
+import org.webrtc.ContextUtils;
+import org.webrtc.EglBase;
+import org.webrtc.GlRectDrawer;
+import org.webrtc.SurfaceViewRenderer;
+
+public class MainActivity extends Activity {
+  private CallClient callClient;
+  private EglBase eglBase;
+  private SurfaceViewRenderer localRenderer;
+  private SurfaceViewRenderer remoteRenderer;
+
+  @Override
+  protected void onCreate(Bundle savedInstance) {
+    ContextUtils.initialize(getApplicationContext());
+
+    super.onCreate(savedInstance);
+    setContentView(R.layout.activity_main);
+
+    System.loadLibrary("examples_androidnativeapi_jni");
+    callClient = new CallClient();
+
+    Button callButton = (Button) findViewById(R.id.call_button);
+    callButton.setOnClickListener((view) -> { callClient.call(localRenderer, remoteRenderer); });
+
+    Button hangupButton = (Button) findViewById(R.id.hangup_button);
+    hangupButton.setOnClickListener((view) -> { callClient.hangup(); });
+  }
+
+  @Override
+  protected void onStart() {
+    super.onStart();
+
+    eglBase = EglBase.create(null /* sharedContext */, EglBase.CONFIG_PLAIN);
+    localRenderer = (SurfaceViewRenderer) findViewById(R.id.local_renderer);
+    remoteRenderer = (SurfaceViewRenderer) findViewById(R.id.remote_renderer);
+
+    localRenderer.init(eglBase.getEglBaseContext(), null /* rendererEvents */, EglBase.CONFIG_PLAIN,
+        new GlRectDrawer());
+    remoteRenderer.init(eglBase.getEglBaseContext(), null /* rendererEvents */,
+        EglBase.CONFIG_PLAIN, new GlRectDrawer());
+  }
+
+  @Override
+  protected void onStop() {
+    callClient.hangup();
+
+    localRenderer.release();
+    remoteRenderer.release();
+    eglBase.release();
+
+    localRenderer = null;
+    remoteRenderer = null;
+    eglBase = null;
+
+    super.onStop();
+  }
+
+  @Override
+  protected void onDestroy() {
+    callClient.close();
+    callClient = null;
+
+    super.onDestroy();
+  }
+}