Created a java wrapper for the callback OnAddTrack to PeerConnection.Observer

webrtc/api/androidtests/src/org/webrtc/PeerConnectionTest.java

Index: webrtc/api/androidtests/src/org/webrtc/PeerConnectionTest.java
diff --git a/webrtc/api/androidtests/src/org/webrtc/PeerConnectionTest.java b/webrtc/api/androidtests/src/org/webrtc/PeerConnectionTest.java
index a4cb3093bc082562d25b46d0bea9b06d0c4f1506..0deecea63f5e8ec32ac6ccb568f2e63145eba94d 100644
--- a/webrtc/api/androidtests/src/org/webrtc/PeerConnectionTest.java
+++ b/webrtc/api/androidtests/src/org/webrtc/PeerConnectionTest.java
@@ -53,6 +53,7 @@ public class PeerConnectionTest extends ActivityTestCase {
     private int expectedWidth = 0;
     private int expectedHeight = 0;
     private int expectedFramesDelivered = 0;
+    private int expectedTracksAdded = 0;
     private LinkedList<SignalingState> expectedSignalingChanges = new LinkedList<SignalingState>();
     private LinkedList<IceConnectionState> expectedIceConnectionChanges =
         new LinkedList<IceConnectionState>();
@@ -225,6 +226,15 @@ public class PeerConnectionTest extends ActivityTestCase {
       assertTrue(--expectedRenegotiations >= 0);
     }
 
+    public synchronized void expectAddTrack(int expectedTracksAdded) {
+      this.expectedTracksAdded = expectedTracksAdded;
+    }
+
+    @Override
+    public synchronized void onAddTrack(RtpReceiver receiver, MediaStream[] mediaStreams) {
+      expectedTracksAdded--;
+    }
+
     public synchronized void expectMessage(ByteBuffer expectedBuffer, boolean expectedBinary) {
       expectedBuffers.add(new DataChannel.Buffer(expectedBuffer, expectedBinary));
     }
@@ -314,6 +324,9 @@ public class PeerConnectionTest extends ActivityTestCase {
       if (expectedStatsCallbacks != 0) {
         stillWaitingForExpectations.add("expectedStatsCallbacks: " + expectedStatsCallbacks);
       }
+      if (expectedTracksAdded != 0) {
+        stillWaitingForExpectations.add("expectedAddedTrack: " + expectedTracksAdded);
+      }
       return stillWaitingForExpectations;
     }
 
@@ -546,6 +559,9 @@ public class PeerConnectionTest extends ActivityTestCase {
         addTracksToPC(factory, offeringPC, videoSource, "offeredMediaStream", "offeredVideoTrack",
             "offeredAudioTrack", new ExpectedResolutionSetter(answeringExpectations));
 
+    offeringExpectations.expectAddTrack(2);
+    answeringExpectations.expectAddTrack(2);
+
     offeringExpectations.expectRenegotiationNeeded();
     DataChannel offeringDC = offeringPC.createDataChannel("offeringDC", new DataChannel.Init());
     assertEquals("offeringDC", offeringDC.label());
@@ -715,7 +731,7 @@ public class PeerConnectionTest extends ActivityTestCase {
   }
 
   @MediumTest
-  public void testTrackRemoval() throws Exception {
+  public void testTrackRemovalAndAddition() throws Exception {
     // Allow loopback interfaces too since our Android devices often don't
     // have those.
     PeerConnectionFactory.Options options = new PeerConnectionFactory.Options();
@@ -752,6 +768,8 @@ public class PeerConnectionTest extends ActivityTestCase {
         addTracksToPC(factory, offeringPC, videoSource, "offeredMediaStream", "offeredVideoTrack",
             "offeredAudioTrack", new ExpectedResolutionSetter(answeringExpectations));
 
+    offeringExpectations.expectAddTrack(2);
+    answeringExpectations.expectAddTrack(2);
     // Create offer.
     SdpObserverLatch sdpLatch = new SdpObserverLatch();
     offeringPC.createOffer(sdpLatch, new MediaConstraints());
@@ -850,50 +868,7 @@ public class PeerConnectionTest extends ActivityTestCase {
     // Note that when we call removeTrack, we regain responsibility for
     // disposing of the track.
     oLMS.get().removeTrack(offererVideoTrack);
-
-    // Create offer.
-    sdpLatch = new SdpObserverLatch();
-    offeringPC.createOffer(sdpLatch, new MediaConstraints());
-    assertTrue(sdpLatch.await());
-    offerSdp = sdpLatch.getSdp();
-    assertEquals(offerSdp.type, SessionDescription.Type.OFFER);
-    assertFalse(offerSdp.description.isEmpty());
-
-    // Set local description for offerer.
-    sdpLatch = new SdpObserverLatch();
-    offeringExpectations.expectSignalingChange(SignalingState.HAVE_LOCAL_OFFER);
-    offeringPC.setLocalDescription(sdpLatch, offerSdp);
-    assertTrue(sdpLatch.await());
-    assertNull(sdpLatch.getSdp());
-
-    // Set remote description for answerer.
-    sdpLatch = new SdpObserverLatch();
-    answeringExpectations.expectSignalingChange(SignalingState.HAVE_REMOTE_OFFER);
-    answeringPC.setRemoteDescription(sdpLatch, offerSdp);
-    assertTrue(sdpLatch.await());
-    assertNull(sdpLatch.getSdp());
-
-    // Create answer.
-    sdpLatch = new SdpObserverLatch();
-    answeringPC.createAnswer(sdpLatch, new MediaConstraints());
-    assertTrue(sdpLatch.await());
-    answerSdp = sdpLatch.getSdp();
-    assertEquals(answerSdp.type, SessionDescription.Type.ANSWER);
-    assertFalse(answerSdp.description.isEmpty());
-
-    // Set local description for answerer.
-    sdpLatch = new SdpObserverLatch();
-    answeringExpectations.expectSignalingChange(SignalingState.STABLE);
-    answeringPC.setLocalDescription(sdpLatch, answerSdp);
-    assertTrue(sdpLatch.await());
-    assertNull(sdpLatch.getSdp());
-
-    // Set remote description for offerer.
-    sdpLatch = new SdpObserverLatch();
-    offeringExpectations.expectSignalingChange(SignalingState.STABLE);
-    offeringPC.setRemoteDescription(sdpLatch, answerSdp);
-    assertTrue(sdpLatch.await());
-    assertNull(sdpLatch.getSdp());
+    negotiate(offeringPC, offeringExpectations, answeringPC, answeringExpectations);
 
     // Make sure the track was really removed.
     // TODO(deadbeef): Currently the expectation is that the video track's
@@ -903,17 +878,50 @@ public class PeerConnectionTest extends ActivityTestCase {
     MediaStream aRMS = answeringExpectations.gotRemoteStreams.iterator().next();
     assertEquals(aRMS.videoTracks.get(0).state(), MediaStreamTrack.State.ENDED);
 
+    // Add the video track to test if the answeringPC will create a new track
+    // for the updated remote description.
+    oLMS.get().addTrack(offererVideoTrack);
+    // The answeringPC sets the updated remote description with a track added.
+    // So the onAddTrack is expected to be called once.

[Taylor Brandstetter, 2016/11/17 23:02:53]

nit: "the onAddTrack callback"

[Zhi Huang, 2016/11/18 02:22:11]

Done.

+    answeringExpectations.expectAddTrack(1);
+    offeringExpectations.expectAddTrack(0);
+    negotiate(offeringPC, offeringExpectations, answeringPC, answeringExpectations);
+
     // Finally, remove the audio track as well, which should completely remove

[Taylor Brandstetter, 2016/11/17 23:02:53]

This comment should be updated.

[Zhi Huang, 2016/11/18 02:22:11]

Done.

     // the remote stream. This used to trigger an assert.
     // See: https://bugs.chromium.org/p/webrtc/issues/detail?id=5128
+    oLMS.get().removeTrack(offererVideoTrack);
     AudioTrack offererAudioTrack = oLMS.get().audioTracks.get(0);
     oLMS.get().removeTrack(offererAudioTrack);
 
+    answeringExpectations.expectRemoveStream("offeredMediaStream");
+    negotiate(offeringPC, offeringExpectations, answeringPC, answeringExpectations);
+
+    // Make sure the stream was really removed.
+    assertTrue(answeringExpectations.gotRemoteStreams.isEmpty());
+
+    // Free the Java-land objects and collect them.
+    shutdownPC(offeringPC, offeringExpectations);
+    offeringPC = null;
+    shutdownPC(answeringPC, answeringExpectations);
+    answeringPC = null;
+    offererVideoTrack.dispose();
+    offererAudioTrack.dispose();
+    videoCapturer.stopCapture();
+    videoCapturer.dispose();
+    videoSource.dispose();
+    factory.dispose();
+    System.gc();
+  }
+
+  private static void negotiate(PeerConnection offeringPC,
+      ObserverExpectations offeringExpectations, PeerConnection answeringPC,
+      ObserverExpectations answeringExpectations) {
     // Create offer.
-    sdpLatch = new SdpObserverLatch();
+    SdpObserverLatch sdpLatch = new SdpObserverLatch();
     offeringPC.createOffer(sdpLatch, new MediaConstraints());
     assertTrue(sdpLatch.await());
-    offerSdp = sdpLatch.getSdp();
+    SessionDescription offerSdp = sdpLatch.getSdp();
     assertEquals(offerSdp.type, SessionDescription.Type.OFFER);
     assertFalse(offerSdp.description.isEmpty());
 
@@ -927,7 +935,6 @@ public class PeerConnectionTest extends ActivityTestCase {
     // Set remote description for answerer.
     sdpLatch = new SdpObserverLatch();
     answeringExpectations.expectSignalingChange(SignalingState.HAVE_REMOTE_OFFER);
-    answeringExpectations.expectRemoveStream("offeredMediaStream");
     answeringPC.setRemoteDescription(sdpLatch, offerSdp);
     assertTrue(sdpLatch.await());
     assertNull(sdpLatch.getSdp());
@@ -936,7 +943,7 @@ public class PeerConnectionTest extends ActivityTestCase {
     sdpLatch = new SdpObserverLatch();
     answeringPC.createAnswer(sdpLatch, new MediaConstraints());
     assertTrue(sdpLatch.await());
-    answerSdp = sdpLatch.getSdp();
+    SessionDescription answerSdp = sdpLatch.getSdp();
     assertEquals(answerSdp.type, SessionDescription.Type.ANSWER);
     assertFalse(answerSdp.description.isEmpty());
 
@@ -953,22 +960,6 @@ public class PeerConnectionTest extends ActivityTestCase {
     offeringPC.setRemoteDescription(sdpLatch, answerSdp);
     assertTrue(sdpLatch.await());
     assertNull(sdpLatch.getSdp());
-
-    // Make sure the stream was really removed.
-    assertTrue(answeringExpectations.gotRemoteStreams.isEmpty());
-
-    // Free the Java-land objects and collect them.
-    shutdownPC(offeringPC, offeringExpectations);
-    offeringPC = null;
-    shutdownPC(answeringPC, answeringExpectations);
-    answeringPC = null;
-    offererVideoTrack.dispose();
-    offererAudioTrack.dispose();
-    videoCapturer.stopCapture();
-    videoCapturer.dispose();
-    videoSource.dispose();
-    factory.dispose();
-    System.gc();
   }
 
   private static void getMetrics() {