Add VideoSink interface to SurfaceViewRenderer.

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

Index: webrtc/sdk/android/api/org/webrtc/VideoRenderer.java
diff --git a/webrtc/sdk/android/api/org/webrtc/VideoRenderer.java b/webrtc/sdk/android/api/org/webrtc/VideoRenderer.java
index d247f21821556728e3b17029ad8b5b637e870ac4..a118efe5feb4e0b7a4018ceb7f9807cd6cbebdd2 100644
--- a/webrtc/sdk/android/api/org/webrtc/VideoRenderer.java
+++ b/webrtc/sdk/android/api/org/webrtc/VideoRenderer.java
@@ -135,6 +135,21 @@ public class VideoRenderer {
           : "Texture: " + textureId;
       return width + "x" + height + ", " + type;
     }
+
+    VideoFrame toVideoFrame() {
+      final VideoFrame.Buffer buffer;
+      if (yuvFrame) {
+        buffer = new I420BufferImpl(width, height, yuvPlanes[0], yuvStrides[0], yuvPlanes[1],
+            yuvStrides[1], yuvPlanes[2], yuvStrides[2],
+            () -> { VideoRenderer.renderFrameDone(this); });
+      } else {
+        // Note: surfaceTextureHelper being null means calling toI420 will crash.
+        buffer = new TextureBufferImpl(width, height, VideoFrame.TextureBuffer.Type.OES, textureId,
+            RendererCommon.convertMatrixToAndroidGraphicsMatrix(samplingMatrix),
+            null /* surfaceTextureHelper */, () -> { VideoRenderer.renderFrameDone(this); });
+      }
+      return new VideoFrame(buffer, rotationDegree, 0 /* timestampNs */);
+    }
   }
 
   // Helper native function to do a video frame plane copying.