Bloomberg: Google plans to unveil a “buy” button for its advertising service, stepping up pressure on rival Amazon as the web company moves deeper into online commerce. The tool, which will let users purchase items from Google’s search results pages, is “imminent,” chief business officer Omid Kordestani said. Google is looking for new ways to keep users on its services as it seeks to boost sales. The company is under growing pressure from Amazon and other e-commerce companies as consumers increasingly shop for items on the web without going through Google’s search service.