Roll src/third_party/ffmpeg/ a77cdbfeb..38d84d205 (4 commits).

https://chromium.googlesource.com/chromium/third_party/ffmpeg.git/+log/a77cdbfeb7b6..38d84d205cd8 (4 commits).

$ git log a77cdbfeb..38d84d205 --date=short --no-merges --format='%ad %ae %s'
2017-02-13 wolenetz Remove cherry-picks from chromium/patches/README
2017-02-13 wolenetz lavf/mov.c: Avoid OOB in mov_read_udta_string()
2017-02-10 wolenetz lavf/mov.c: Avoid heap allocation wraps in mov_read_{senc,saiz}()
2017-02-10 dalecurtis h264dec: handle zero-sized NAL units in get_last_needed_nal()

Created with:
  roll-dep src/third_party/ffmpeg

R=dalecurtis@chromium.org
TBR=hubbe@chromium.org

BUG=643952,690184

Review-Url: https://codereview.chromium.org/2694913002
Cr-Commit-Position: refs/heads/master@{#450178}
diff --git a/DEPS b/DEPS
index e479185..fc62d16b 100644
--- a/DEPS
+++ b/DEPS
@@ -205,7 +205,7 @@
     Var('chromium_git') + '/webm/libvpx.git' + '@' +  '91f87e75135cc9722ee72daf5154424f628a906e',
 
   'src/third_party/ffmpeg':
-    Var('chromium_git') + '/chromium/third_party/ffmpeg.git' + '@' + 'a77cdbfeb7b629eb3a5012d7c6c94ef11e0488be',
+    Var('chromium_git') + '/chromium/third_party/ffmpeg.git' + '@' + '38d84d205cd89cb9ce740735d2d31d4bc2a07abb',
 
   'src/third_party/usrsctp/usrsctplib':
     Var('chromium_git') + '/external/github.com/sctplab/usrsctp' + '@' + '8679f2b0bf063ac894dc473debefd61dbbebf622',