Joe Rossignol reporting for MacRumors:
Apple’s leadership page is only now reflecting Federighi’s role as head of Siri, but the transition has been apparent for several months, based on recent interviews and stage appearances at Apple’s keynotes.
Eddie Cue is in charge of the products that require deal-making with third parties. Apple Music & Apple Pay fall under his purview. Siri did start off by integrating directly with services via deals with third parties such as Wolfram Alpha, but that seems to have stopped in favor of an API. So now, having Craig be in charge of another core piece of the OSes he manages seems like a no-brainer.