Use ffmpeg_features buildflags

media/filters/ffmpeg_demuxer.cc

Index: media/filters/ffmpeg_demuxer.cc
diff --git a/media/filters/ffmpeg_demuxer.cc b/media/filters/ffmpeg_demuxer.cc
index 136fe32a7b9ab469020a8e9c0a606af25c3cb0ef..40a8564104ef961bec849d34bf6a93da846c1a3e 100644
--- a/media/filters/ffmpeg_demuxer.cc
+++ b/media/filters/ffmpeg_demuxer.cc
@@ -42,6 +42,7 @@
 #include "media/filters/webvtt_util.h"
 #include "media/formats/webm/webm_crypto_helpers.h"
 #include "media/media_features.h"
+#include "third_party/ffmpeg/ffmpeg_features.h"
 
 #if BUILDFLAG(ENABLE_HEVC_DEMUXING)
 #include "media/filters/ffmpeg_h265_to_annex_b_bitstream_converter.h"
@@ -1247,7 +1248,7 @@ void FFmpegDemuxer::OnFindStreamInfoDone(const PipelineStatusCB& status_cb,
   // If no estimate is found, the stream entry will be kInfiniteDuration.
   std::vector<base::TimeDelta> start_time_estimates(format_context->nb_streams,
                                                     kInfiniteDuration);
-#if !defined(USE_SYSTEM_FFMPEG)
+#if !BUILDFLAG(USE_SYSTEM_FFMPEG)
   const AVFormatInternal* internal = format_context->internal;
   if (internal && internal->packet_buffer &&
       format_context->start_time != static_cast<int64_t>(AV_NOPTS_VALUE)) {
@@ -1271,7 +1272,7 @@ void FFmpegDemuxer::OnFindStreamInfoDone(const PipelineStatusCB& status_cb,
       packet_buffer = packet_buffer->next;
     }
   }
-#endif  // !defined(USE_SYSTEM_FFMPEG)
+#endif  // !BUILDFLAG(USE_SYSTEM_FFMPEG)
 
   std::unique_ptr<MediaTracks> media_tracks(new MediaTracks());