Mike Dirnt has a lot to reflect on right now. Green Day just released its 14th album to global acclaim, while also celebrating the 30th and 20th anniversaries of the mega-albums Dookie (1994) and American Idiot (2014). Green Day’s latest offering, Saviors, found the band reuniting with producer Rob Cavallo in a full-circle journey where Dirnt found his favorite sound yet. The 51-year-old punk rocker is nearing four decades in the band, after a chance meeting with Billie Joe Armstrong in his early teens, and later drummer Tré Cool, led to rock stardom for most of his life. He thinks a lot about these things while he joyrides his motorcycles up the Bay Area coast, catches waves atop his surfboard, and tends to the coffee company he co-founded, Oakland Coffee Works. But the thing he’s thinking about today, as he does a lot of the time, is bass.    Since the first moment he played one, he knew the instrument would be his path, as his turbulen