No, Shaun White was not snowboarding on Mars. These tracks, captured by NASA's Mars Reconnaissance Orbiter, are thought to have been created from sliding dry ice on the Red Planet's Russell Crater.
In the video below, Serina Diniega, a planetary scientist at NASA's Jet Propulsion Laboratory, explains how these linear gullies, as these tracks are called, were formed by dry ice sleds.
Image credit: NASA/JPL-Caltech/Univ. of Arizona