This is the logo for the B button on an XBox controller. It has a capital letter "B" inside of a circle which resembles the button found on all XBox controllers.
This Xbox B icon is made in Material Design style
developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 5,700 icons, all in the same style and quality.