New FFmpeg public API headers to match our source tarball in deps.

media/filters/ffmpeg_demuxer_unittest.cc

Index: media/filters/ffmpeg_demuxer_unittest.cc
diff --git a/media/filters/ffmpeg_demuxer_unittest.cc b/media/filters/ffmpeg_demuxer_unittest.cc
index 6b4f06d942128068c346d95d8d5c0527f15269c7..157f2ae4642b0265a57e18c2d5111e7c640786fc 100644
--- a/media/filters/ffmpeg_demuxer_unittest.cc
+++ b/media/filters/ffmpeg_demuxer_unittest.cc
@@ -143,6 +143,14 @@ int64 av_rescale_q(int64 a, AVRational bq, AVRational cq) {
   return a * num / den;
 }
 
+void av_free_packet(AVPacket* packet) {
+  if (packet->destruct) {
+    packet->destruct(packet);
+    packet->data = NULL;
+    packet->size = 0;
+  }
+}
+
 void DestructPacket(AVPacket* packet) {
   delete [] packet->data;
   --g_outstanding_packets_av_new_frame;