The bundled ffmpeg in Chromium is newer than the one in Guix.  Patch so
we can build with the new and old ffmpeg versions.

Taken from Gentoo:
https://gitweb.gentoo.org/repo/gentoo.git/tree/www-client/chromium/files/chromium-93-fix-build-with-system-ffmpeg.patch

diff --git a/media/filters/audio_decoder_unittest.cc b/media/filters/audio_decoder_unittest.cc
--- a/media/filters/audio_decoder_unittest.cc
+++ b/media/filters/audio_decoder_unittest.cc
@@ -109,7 +109,11 @@ void SetDiscardPadding(AVPacket* packet,
   }
 
   // If the timestamp is positive, try to use FFmpeg's discard data.
+#if LIBAVUTIL_VERSION_MAJOR < 57
+  int skip_samples_size = 0;
+#else
   size_t skip_samples_size = 0;
+#endif
   const uint32_t* skip_samples_ptr =
       reinterpret_cast<const uint32_t*>(av_packet_get_side_data(
           packet, AV_PKT_DATA_SKIP_SAMPLES, &skip_samples_size));
diff --git a/media/filters/ffmpeg_demuxer.cc b/media/filters/ffmpeg_demuxer.cc
--- a/media/filters/ffmpeg_demuxer.cc
+++ b/media/filters/ffmpeg_demuxer.cc
@@ -427,11 +427,19 @@ void FFmpegDemuxerStream::EnqueuePacket(
   scoped_refptr<DecoderBuffer> buffer;
 
   if (type() == DemuxerStream::TEXT) {
+#if LIBAVUTIL_VERSION_MAJOR < 57
+    int id_size = 0;
+#else
     size_t id_size = 0;
+#endif
     uint8_t* id_data = av_packet_get_side_data(
         packet.get(), AV_PKT_DATA_WEBVTT_IDENTIFIER, &id_size);
 
+#if LIBAVUTIL_VERSION_MAJOR < 57
+    int settings_size = 0;
+#else
     size_t settings_size = 0;
+#endif
     uint8_t* settings_data = av_packet_get_side_data(
         packet.get(), AV_PKT_DATA_WEBVTT_SETTINGS, &settings_size);
 
@@ -443,7 +451,11 @@ void FFmpegDemuxerStream::EnqueuePacket(
     buffer = DecoderBuffer::CopyFrom(packet->data, packet->size,
                                      side_data.data(), side_data.size());
   } else {
+#if LIBAVUTIL_VERSION_MAJOR < 57
+    int side_data_size = 0;
+#else
     size_t side_data_size = 0;
+#endif
     uint8_t* side_data = av_packet_get_side_data(
         packet.get(), AV_PKT_DATA_MATROSKA_BLOCKADDITIONAL, &side_data_size);
 
@@ -504,7 +516,11 @@ void FFmpegDemuxerStream::EnqueuePacket(
                                        packet->size - data_offset);
     }
 
+#if LIBAVUTIL_VERSION_MAJOR < 57
+    int skip_samples_size = 0;
+#else
     size_t skip_samples_size = 0;
+#endif
     const uint32_t* skip_samples_ptr =
         reinterpret_cast<const uint32_t*>(av_packet_get_side_data(
             packet.get(), AV_PKT_DATA_SKIP_SAMPLES, &skip_samples_size));
eft'>Author</th></tr>
<tr><td><span title='2020-03-23 00:06:58 +0100'>2020-03-23</span></td><td><a href='/guix/commit/etc/system-tests.scm?id=8b18f5cb309f670b08ad35df6425f4e9e19d8a82'>tests: Use the same source as ci.guix.gnu.org.</a><span class='msg-avail'>...<span class='msg-tooltip'>* etc/system-tests.scm (system-test-manifest): In 'local-file' call, use
a name that is a function of COMMIT to match what Cuirass does.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-03-05 16:33:38 +0100'>2020-03-05</span></td><td><a href='/guix/commit/etc/system-tests.scm?id=5ec4156bbcaec8337f78411204d59e59e706103b'>tests: Add a manifest for system tests.</a><span class='msg-avail'>...<span class='msg-tooltip'>The manifest can be passed to 'guix build -m', 'guix weather -m', and so
on.  It can also be passed to an installed 'guix' (without
./pre-inst-env), with the exception so far of installation tests.

* build-aux/run-system-tests.scm: Remove.  Move interesting bits move
to...
* etc/system-tests.scm: ... here.  New file.
* Makefile.am (EXTRA_DIST): Remove 'build-aux/run-system-tests.scm' and
add 'etc/system-tests.scm'.
(check-system): Rewrite to run 'guix build -m etc/system-tests.scm'.
</span></span></td><td>Ludovic Courtès</td></tr>