Fix implicit size_t to uint16_t warning on VS2015.
Fix implicit size_t to uint16_t warning on VS2015.

Reviewed as https://review.webrtc.org/54609004/, but uploaded against
wrong Base URL.

R=pbos@webrtc.org
TBR=
BUG=chromium:440500

Review URL: https://webrtc-codereview.appspot.com/54649004

Patch from scottmg <scottmg@chromium.org>.

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#9351}

ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc