Add missing include in EGLWindow.cpp BUG=angleproject:892 Change-Id: I23cfbd9cfbe7d41e048a2b2a4eea048f5de72d12 Reviewed-on: https://chromium-review.googlesource.com/269123 Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Corentin Wallez <cwallez@chromium.org>