Android: Allow injecting native PeerConnection.

This allows application to construct PeerConnection object in JNI and
pass that to Android API. API for wrapping Java PeerConnection Observers
is exposed for convenience.

Bug: webrtc:8662
Change-Id: Id110b92e6bb5ab00661cd50616d05c3e18a1697d
Reviewed-on: https://webrtc-review.googlesource.com/34520
Commit-Queue: Sami Kalliomäki <sakal@webrtc.org>
Reviewed-by: Jonas Oreland <jonaso@webrtc.org>
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21379}

sdk/android/BUILD.gn

@@ -587,6 +587,7 @@ rtc_android_library("libjingle_peerconnection_java") {
     "api/org/webrtc/MediaStream.java",
     "api/org/webrtc/MediaStreamTrack.java",
     "api/org/webrtc/NativeLibraryLoader.java",
+    "api/org/webrtc/NativePeerConnectionFactory.java",
     "api/org/webrtc/NetworkMonitor.java",
     "api/org/webrtc/NetworkMonitorAutoDetect.java",
     "api/org/webrtc/PeerConnection.java",
@@ -606,8 +607,8 @@ rtc_android_library("libjingle_peerconnection_java") {
     "api/org/webrtc/SoftwareVideoEncoderFactory.java",
     "api/org/webrtc/StatsObserver.java",
     "api/org/webrtc/StatsReport.java",
-    "api/org/webrtc/SurfaceTextureHelper.java",
     "api/org/webrtc/SurfaceEglRenderer.java",
+    "api/org/webrtc/SurfaceTextureHelper.java",
     "api/org/webrtc/SurfaceViewRenderer.java",
     "api/org/webrtc/TurnCustomizer.java",
     "api/org/webrtc/VideoCapturer.java",

sdk/android/api/org/webrtc/NativePeerConnectionFactory.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::PeerConnectionInterface instances. */
+public interface NativePeerConnectionFactory {
+  /**
+   * Create a new webrtc::PeerConnectionInterface instance and returns a pointer to it.
+   * The caller takes ownership of the object.
+   */
+  long createNativePeerConnection();
+}

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

@@ -551,6 +551,14 @@ public class PeerConnection {
   private List<RtpSender> senders = new ArrayList<>();
   private List<RtpReceiver> receivers = new ArrayList<>();
 
+  /**
+   * Wraps a PeerConnection created by the factory. Can be used by clients that want to implement
+   * their PeerConnection creation in JNI.
+   */
+  public PeerConnection(NativePeerConnectionFactory factory) {
+    this(factory.createNativePeerConnection(), 0 /* nativeObserver */);
+  }
+
   PeerConnection(long nativePeerConnection, long nativeObserver) {
     this.nativePeerConnection = nativePeerConnection;
     this.nativeObserver = nativeObserver;
@@ -745,7 +753,9 @@ public class PeerConnection {
     }
     receivers.clear();
     JniCommon.nativeReleaseRef(nativePeerConnection);
-    freeObserver(nativeObserver);
+    if (nativeObserver != 0) {
+      freeNativePeerConnectionObserver(nativeObserver);
+    }
   }
 
   @CalledByNative
@@ -753,7 +763,8 @@ public class PeerConnection {
     return nativePeerConnection;
   }
 
-  private static native void freeObserver(long nativeObserver);
+  public static native long createNativePeerConnectionObserver(Observer observer);
+  public static native void freeNativePeerConnectionObserver(long nativeObserver);
 
   private native boolean setNativeConfiguration(RTCConfiguration config, long nativeObserver);
 

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

@@ -226,7 +226,7 @@ public class PeerConnectionFactory {
   @Deprecated
   public PeerConnection createPeerConnection(PeerConnection.RTCConfiguration rtcConfig,
       MediaConstraints constraints, PeerConnection.Observer observer) {
-    long nativeObserver = createNativeObserver(observer);
+    long nativeObserver = PeerConnection.createNativePeerConnectionObserver(observer);
     if (nativeObserver == 0) {
       return null;
     }
@@ -388,8 +388,6 @@ public class PeerConnectionFactory {
       VideoEncoderFactory encoderFactory, VideoDecoderFactory decoderFactory,
       long nativeAudioProcessor);
 
-  private static native long createNativeObserver(PeerConnection.Observer observer);
-
   private static native long createNativePeerConnection(long nativeFactory,
       PeerConnection.RTCConfiguration rtcConfig, MediaConstraints constraints, long nativeObserver);
 

sdk/android/src/jni/pc/peerconnection.cc

@@ -440,8 +440,16 @@ jobjectArray PeerConnectionObserverJni::NativeToJavaMediaStreamArray(
   return java_streams;
 }
 
+JNI_FUNCTION_DECLARATION(jlong,
+                         PeerConnection_createNativePeerConnectionObserver,
+                         JNIEnv* jni,
+                         jclass,
+                         jobject j_observer) {
+  return jlongFromPointer(new PeerConnectionObserverJni(jni, j_observer));
+}
+
 JNI_FUNCTION_DECLARATION(void,
-                         PeerConnection_freeObserver,
+                         PeerConnection_freeNativePeerConnectionObserver,
                          JNIEnv*,
                          jclass,
                          jlong j_p) {

sdk/android/src/jni/pc/peerconnectionfactory.cc

@@ -93,14 +93,6 @@ void PeerConnectionFactorySignalingThreadReady() {
   Java_PeerConnectionFactory_onSignalingThreadReady(env);
 }
 
-JNI_FUNCTION_DECLARATION(jlong,
-                         PeerConnectionFactory_createNativeObserver,
-                         JNIEnv* jni,
-                         jclass,
-                         jobject j_observer) {
-  return (jlong) new PeerConnectionObserverJni(jni, j_observer);
-}
-
 JNI_FUNCTION_DECLARATION(void,
                          PeerConnectionFactory_initializeNativeAndroidGlobals,
                          JNIEnv* jni,