Libvpx roll.

See https://codereview.chromium.org/23600008/
https://codereview.chromium.org/23493010/
for the actual changes.

BUG=279335
R=scherkus@chromium.org

Review URL: https://codereview.chromium.org/23532005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@220587 0039d316-1c4b-4281-b951-d872f2087c98

DEPS

@@ -20,7 +20,7 @@ vars = {
   "gtm_revision": "616",
 
   "libphonenumber_revision": "584",
-  "libvpx_revision": "212364",
+  "libvpx_revision": "219848",
   "lss_revision": "20",
 
   # These two FFmpeg variables must be updated together.  One is used for SVN