This patch fixes user-agent reported for iPad 3/4 emulation.

BUG=328677
TBR=vsevik

Review URL: https://codereview.chromium.org/115833002

git-svn-id: svn://svn.chromium.org/blink/trunk@163913 bbb929c8-8fbe-4397-9dbb-9b2b20218538