Turns out the processor/SoC in the latest two ChromeBooks - the Samsung models - are part of a wider program by Google.
The OP1 is built by Rockchip, which has made ARM processors for a while and isn't especially well-regarded among US consumers. And, strangely enough, even discovering that Rockchip makes the OP1 took a bit of sleuthing. The company doesn't have its brand anywhere near the Chromebook Plus. Also, the chip is called the OP1, which implies that there's going to be an OP2 and OP3 and so on. What exactly is going on here? Just what is OP?
Well! Turns out there's a website for answering that exact question, helpfully named whatisop.com. OP is a designation for SoCs that are optimized for Chrome OS. Naturally, I assumed it was a Rockchip brand - but that's not the case at all. And the website ostensibly designed to explain OP to us doesn't tell us who owns it (and it's even registered anonymously), so OP strangely mysterious.
Mystery solved: OP is a trademark owned by Google, and bestowed on SoCs that meet a Google spec for a good Chrome OS device. Basically, if a Chromebook has an OP processor, it means that Google certifies that it’s been optimized for Chrome OS.
Everybody is racing towards ARM laptops. Intel's decision to sell Xscale is probably going to be looked back upon as one of the worst decisions in technology history.