If Chrome is "from scratch", then I'm having trouble understanding what making something not from scratch is. It's got to contrast with something to have any me

If Chrome is "from scratch", then I'm having trouble understanding what making something not from scratch is. It's got to contrast with something to have any meaning. Where to draw the line? 1 Tool written as an Excel spreadsheet. 2 Custom IDE built on Eclipse. 3 Web browser using someone else's rendering engine. 4 Banshee music player running on Mono. 5 Pure native app calling only operating system supplied libraries. But I suppose you could also read it in the sense of "from a blank slate". It seems to make more sense this way.