We would print non-casted unsigned char output, giving an an ascii
code on output, instead of printing the integer value of the size
field.

BUG=angle:539

Change-Id: I963c297d01df6283825d684ada7a34fd535f2550
Reviewed-on: https://chromium-review.googlesource.com/180650Reviewed-by: Nicolas Capens <nicolascapens@chromium.org>
Commit-Queue: Nicolas Capens <nicolascapens@chromium.org>
Tested-by: Nicolas Capens <nicolascapens@chromium.org>
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>