Music honcho Lyor Cohen played hardball with YouTube for years then shocked everyone by joining the

   Lyor Cohen spent 30 years in the recorded-music industry and then after witnessing the rise of digital distribution, he swapped sides. As  YouTube's global head of music, he is overseeing the launch of YouTube's new subscription service. Cohen isn't just a former music industry insider. He waged a bare-knuckled public-relations fight against YouTube a decade ago when the two companies failed to come to terms on a licensing deal.  Cohen's renaissance as a digital executive may seem...