[Experiment] Alpha Channel Support

api/video_codecs/video_encoder.h

Index: api/video_codecs/video_encoder.h
diff --git a/api/video_codecs/video_encoder.h b/api/video_codecs/video_encoder.h
index 505564c1305eaef64a5167ce95519800f65e5705..639e60c4d937f9e8457869a04fcfdb5c7c80febe 100644
--- a/api/video_codecs/video_encoder.h
+++ b/api/video_codecs/video_encoder.h
@@ -179,5 +179,13 @@ class VideoEncoder {
   virtual bool SupportsNativeHandle() const;
   virtual const char* ImplementationName() const;
 };
+
+class VideoEncoderFactoryEx {
+ public:
+  virtual VideoEncoder* Create() = 0;
+  virtual void Destroy(VideoEncoder* encoder) = 0;
+  virtual ~VideoEncoderFactoryEx() {}
+};
+
 }  // namespace webrtc
 #endif  // API_VIDEO_CODECS_VIDEO_ENCODER_H_