Using the C struct initialization syntax was giving errors on
Linux.

BUG=angle:773

Change-Id: I298c851df7246eeb1772837c5678f3c578483b63
Reviewed-on: https://chromium-review.googlesource.com/231854Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>