Google took the wraps off two Chromebook laptop PCs after nearly two years of delays and touts of its Chrome operating system as an alternative to Microsoft Windows. Samsung and Acer laptops using Chrome OS will go on sale June 15, as the world’s No. 1 Internet search engine tries to entice people to do more on the Web. As with Android, Chrome software will be free, but is expected to spur people to use the Internet more often and search for more things, potentially boosting Google’s Internet ads business.