libvpx: Pull from upstream

source/libvpx/vp9/encoder/vp9_bitstream.h

 /*
  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 
 #ifndef VP9_ENCODER_VP9_BITSTREAM_H_
 #define VP9_ENCODER_VP9_BITSTREAM_H_
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-struct VP9_COMP;
+#include "vp9/encoder/vp9_encoder.h"
 
 void vp9_entropy_mode_init();
 
-void vp9_pack_bitstream(struct VP9_COMP *cpi, uint8_t *dest, size_t *size);
+void vp9_pack_bitstream(VP9_COMP *cpi, uint8_t *dest, size_t *size);
+
+static INLINE int vp9_preserve_existing_gf(VP9_COMP *cpi) {
+  return !cpi->multi_arf_allowed && cpi->refresh_golden_frame &&
+         cpi->rc.is_src_frame_alt_ref &&
+         (!cpi->use_svc ||      // Add spatial svc base layer case here
+          (is_spatial_svc(cpi) &&
+           cpi->svc.spatial_layer_id == 0 &&
+           cpi->svc.layer_context[0].gold_ref_idx >=0 &&
+           cpi->oxcf.ss_play_alternate[0]));
+}
 
 #ifdef __cplusplus
 }  // extern "C"
 #endif
 
 #endif  // VP9_ENCODER_VP9_BITSTREAM_H_