With all the, real, new Chromebooks coming out, there's also a surge in rumored ones. The Chromebook Pixel is most definitely a fake, though Google could be working on a more high-end device. However, it seems that there's also a Tegra 4-powered Chromebook in the works.
The Samsung Chromebook already uses an ARM processor, so a Tegra 4 in a Chromebook doesn't seem as far-fetched as it would have sounded a few months ago.
Google is already using Tegra 3 in its Nexus 7 and there's every indication that it will use the Tegra 4 in its second-generation Nexus 7 to be unveiled at Google I/O 2013 this May.
The Tegra 4 also promises to be a lot more powerful than the Samsung Exynos 5 used in the Samsung Chromebook. That's a good thing since the Exynos 5 is a bit too slow for Chrome OS.