Android: Fix synchronization problems in VideoFrame release.

Also fixes a small bug in EglRenderer where if it was passed a custom
frame, it would leak a reference.

BUG=b/64887218

Review-Url: https://codereview.webrtc.org/3003533002
Cr-Commit-Position: refs/heads/master@{#19432}

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

@@ -639,7 +639,7 @@ public class EglRenderer implements VideoRenderer.Callbacks, VideoSink {
     }
 
     notifyCallbacks(frame, isYuvBuffer, yuvTextures, shouldRenderFrame);
-    frame.release();
+    buffer.release();
   }
 
   private void notifyCallbacks(