Bug 1044794 - Part 1: build flag for share overlays. r=nalexander
Bug 1044794 - Part 2: disable Sync share handler when share overlay is enabled. r=rnewman,nalexander
Bug 1044794 - Part 3: a service for handling share intents. r=rnewman
Bug 1044947 - Frontend for share handler. r=rnewman