Fix pointer arithmetic in UTF8ToUTF16Char
Fix pointer arithmetic in UTF8ToUTF16Char

Found by PVS-Studio!

BUG=chromium:660198

Change-Id: I2605de2b1499f85c6e01d19e87e9eeb6af8486f3
Reviewed-on: https://chromium-review.googlesource.com/404552
Reviewed-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>

bittorrent/breakpad,bittorrent/breakpad,bittorrent/breakpad,bittorrent/breakpad,bittorrent/breakpad,bittorrent/breakpad,bittorrent/breakpad