Sony is giving Google’s fledging Chrome browser a boost by installing it as the primary browser on Vaio-brand computers sold in the United States and Europe. The Sony devices continue to provide Microsoft’s Internet Explorer — the world’s most widely used Web — allowing users to have a choice between the two. However, many users stick with the browser that is preset as the default, meaning they are likely to experience Chrome as their primary — perhaps only — gateway to the Web. Sony is the first PC maker to sell computers with Chrome pre-installed.