Extract TL config to VP8 libvpx flag conversion.

webrtc/modules/video_coding/codecs/vp8/vp8_impl.h

Index: webrtc/modules/video_coding/codecs/vp8/vp8_impl.h
diff --git a/webrtc/modules/video_coding/codecs/vp8/vp8_impl.h b/webrtc/modules/video_coding/codecs/vp8/vp8_impl.h
index c33343602605a21a351daaa2770397c5af4a1eff..f07b0f93998c7edeec3a0b9a854ed173cf2912e4 100644
--- a/webrtc/modules/video_coding/codecs/vp8/vp8_impl.h
+++ b/webrtc/modules/video_coding/codecs/vp8/vp8_impl.h
@@ -25,8 +25,9 @@
 
 #include "webrtc/api/video/video_frame.h"
 #include "webrtc/common_video/include/i420_buffer_pool.h"
-#include "webrtc/modules/video_coding/include/video_codec_interface.h"
 #include "webrtc/modules/video_coding/codecs/vp8/include/vp8.h"
+#include "webrtc/modules/video_coding/codecs/vp8/temporal_layers.h"
+#include "webrtc/modules/video_coding/include/video_codec_interface.h"
 #include "webrtc/modules/video_coding/utility/quality_scaler.h"
 #include "webrtc/video_frame.h"
 
@@ -61,6 +62,8 @@ class VP8EncoderImpl : public VP8Encoder {
 
   const char* ImplementationName() const override;
 
+  static vpx_enc_frame_flags_t EncodeFlags(TemporalReferences references);
+
  private:
   void SetupTemporalLayers(int num_streams,
                            int num_temporal_layers,