Bug 836702 Port front end sync lazy init changes from bug 836120 r=IanN
Bug 837492 Detect whether the browser has been opened as a private window r=IanN
Bug 837399 Part 1: make the click-to-play close box work r=Ratty
Bug 837399 Part 2: Modern theme support r=Ratty
Bug 837399 Part 2a: address review comment