Add support for adding VideoSinks to VideoTracks.

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

Index: webrtc/sdk/android/api/org/webrtc/VideoTrack.java
diff --git a/webrtc/sdk/android/api/org/webrtc/VideoTrack.java b/webrtc/sdk/android/api/org/webrtc/VideoTrack.java
index 8118940a0318753b4d4bc9cc9e1882a6d4841799..18a826cb730f76f3c8ae10cf195fc0b5a21d8dd1 100644
--- a/webrtc/sdk/android/api/org/webrtc/VideoTrack.java
+++ b/webrtc/sdk/android/api/org/webrtc/VideoTrack.java
@@ -10,26 +10,55 @@
 
 package org.webrtc;
 
+import java.util.IdentityHashMap;
 import java.util.LinkedList;
 
 /** Java version of VideoTrackInterface. */
 public class VideoTrack extends MediaStreamTrack {
   private final LinkedList<VideoRenderer> renderers = new LinkedList<VideoRenderer>();
+  private final IdentityHashMap<VideoSink, Long> sinks = new IdentityHashMap<VideoSink, Long>();
 
   public VideoTrack(long nativeTrack) {
     super(nativeTrack);
   }
 
+  /**
+   * Adds a VideoSink to the track.
+   *
+   * A track can have any number of VideoSinks. VideoSinks will replace
+   * renderers. However, converting old style texture frames will involve costly
+   * conversion to I420 so it is not recommended to upgrade before all your
+   * sources produce VideoFrames.
+   */
+  public void addSink(VideoSink sink) {
+    final long nativeSink = nativeWrapSink(sink);
+    sinks.put(sink, nativeSink);
+    nativeAddSink(nativeTrack, nativeSink);
+  }
+
+  /**
+   * Removes a VideoSink from the track.
+   *
+   * If the VideoSink was not attached to the track, this is a no-op.
+   */
+  public void removeSink(VideoSink sink) {
+    final long nativeSink = sinks.remove(sink);
+    if (nativeSink != 0) {
+      nativeRemoveSink(nativeTrack, nativeSink);
+      nativeFreeSink(nativeSink);
+    }
+  }
+
   public void addRenderer(VideoRenderer renderer) {
     renderers.add(renderer);
-    nativeAddRenderer(nativeTrack, renderer.nativeVideoRenderer);
+    nativeAddSink(nativeTrack, renderer.nativeVideoRenderer);
   }
 
   public void removeRenderer(VideoRenderer renderer) {
     if (!renderers.remove(renderer)) {
       return;
     }
-    nativeRemoveRenderer(nativeTrack, renderer.nativeVideoRenderer);
+    nativeRemoveSink(nativeTrack, renderer.nativeVideoRenderer);
     renderer.dispose();
   }
 
@@ -37,10 +66,17 @@ public class VideoTrack extends MediaStreamTrack {
     while (!renderers.isEmpty()) {
       removeRenderer(renderers.getFirst());
     }
+    for (long nativeSink : sinks.values()) {
+      nativeRemoveSink(nativeTrack, nativeSink);
+      nativeFreeSink(nativeSink);
+    }
+    sinks.clear();
     super.dispose();
   }
 
-  private static native void nativeAddRenderer(long nativeTrack, long nativeRenderer);
+  private static native void nativeAddSink(long nativeTrack, long nativeSink);
+  private static native void nativeRemoveSink(long nativeTrack, long nativeSink);
 
-  private static native void nativeRemoveRenderer(long nativeTrack, long nativeRenderer);
+  private static native long nativeWrapSink(VideoSink sink);
+  private static native void nativeFreeSink(long nativeSink);
 }