Roll FFmpeg DEPS

Includes cherry-pick to fix aac/ac3 parser bitstream buffer size

BUG=405416
R=dalecurtis@chromium.org
TEST=media_unittests all pass with proprietary codecs with asan

Review URL: https://codereview.chromium.org/499643003

Cr-Commit-Position: refs/heads/master@{#291545}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@291545 0039d316-1c4b-4281-b951-d872f2087c98

DEPS

@@ -219,7 +219,7 @@ deps = {
 
   "src/third_party/ffmpeg":
     Var("chromium_git") +
-    "/chromium/third_party/ffmpeg.git@95a2bce6dad6569ec65b547169f4a9d58877a1f4",
+    "/chromium/third_party/ffmpeg.git@98ca32e50f6e38447bc81705d0689ebceb6ac649",
 
   "src/third_party/libjingle/source/talk":
     (Var("googlecode_url") % "webrtc") + "/trunk/talk@" +