Reland of Initial version of file wrapper

Fixes a conversion issue.

BUG=webrtc:6177
R=sprang@webrtc.org
TBR=mflodman@webrtc.org

patch from issue 2214763002 at patchset 450001 (http://crrev.com/2214763002#ps450001)

Review URL: https://codereview.webrtc.org/2306553002 .

Cr-Original-Commit-Position: refs/heads/master@{#14044}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 4ec6a0ceae0a3d54a46fd4116cd503336ff32a20
9 files changed