Pass HdrMetadata between VideoFrame and EncodedImage for VP9

Bug: webrtc:8651
Change-Id: Ie4d7ee19bead84eda7788076662c4066edc3f024
Reviewed-on: https://webrtc-review.googlesource.com/c/109583
Reviewed-by: Erik Språng <sprang@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Commit-Queue: Johannes Kron <kron@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25581}

modules/video_coding/codecs/vp9/vp9_impl.h

@@ -167,7 +167,8 @@ class VP9DecoderImpl : public VP9Decoder {
   int ReturnFrame(const vpx_image_t* img,
                   uint32_t timestamp,
                   int64_t ntp_time_ms,
-                  int qp);
+                  int qp,
+                  const HdrMetadata* hdr_metadata);
 
   // Memory pool used to share buffers between libvpx and webrtc.
   Vp9FrameBufferPool frame_buffer_pool_;