Revert of FFmpeg roll for M43.

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 535bbcd9625ea93841ad65fb87f9174b2ab6cba8..be31709b05017603df7c655e6e06e417eaef997e 100644
--- a/media/filters/ffmpeg_demuxer.cc
+++ b/media/filters/ffmpeg_demuxer.cc
@@ -838,11 +838,10 @@
   // If no estimate is found, the stream entry will be kInfiniteDuration().
   std::vector<base::TimeDelta> start_time_estimates(format_context->nb_streams,
                                                     kInfiniteDuration());
-  const AVFormatInternal* internal = format_context->internal;
-  if (internal && internal->packet_buffer &&
+  if (format_context->packet_buffer &&
       format_context->start_time != static_cast<int64>(AV_NOPTS_VALUE)) {
-    struct AVPacketList* packet_buffer = internal->packet_buffer;
-    while (packet_buffer != internal->packet_buffer_end) {
+    struct AVPacketList* packet_buffer = format_context->packet_buffer;
+    while (packet_buffer != format_context->packet_buffer_end) {
       DCHECK_LT(static_cast<size_t>(packet_buffer->pkt.stream_index),
                 start_time_estimates.size());
       const AVStream* stream =