Add support for adding VideoSinks to VideoTracks.

VideoSinks receive the new kind of VideoFrames and will replace
VideoRenderers. Converting from old texture frames to VideoFrames will
involve conversion to I420 so it is not recommended to use VideoSinks
before all sources produce VideoFrames.

BUG=webrtc:7749, webrtc:7760

Review-Url: https://codereview.webrtc.org/3002553002
Cr-Commit-Position: refs/heads/master@{#19335}

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

@@ -0,0 +1,23 @@
+/*
+ *  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;
+
+/**
+ * Java version of rtc::VideoSinkInterface.
+ */
+public interface VideoSink {
+  /**
+   * Implementations should call frame.retain() if they need to hold a reference to the frame after
+   * this function returns. Each call to retain() should be followed by a call to frame.release()
+   * when the reference is no longer needed.
+   */
+  void onFrame(VideoFrame frame);
+}

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);
 }