Mayer’s fourth studio CD debuted atop the Billboard charts upon its 2009 release. Here are easy guitar arrangements of the hits “Who Says,” “Heartbreak Warfare” and nine more: All We Ever Do Is Say Goodbye • Assassin • Cross Road Blues (Crossroads) • Do You Know Me • Edge of Desire • Friends, Lovers or Nothing • Half of My Heart • Perfectly Lonely • War of My Life.