Google's Android SDK may be getting a Chrome OS emulator according to details that were discovered in recent code commits. The Android SDK can be used for a number of different things, but one of its main uses is for developers so that they can test out and develop their apps for the Android platform. Considering this it's not hard to imagine what the benefits would be for having a Chrome OS emulator as part of the SDK, as it would allow developers a way to see how their apps might run on the Chrome OS platform should they want to port their apps over.
This could be useful especially since there are a number of Chromebooks which already support Android apps, and more on the way. The more models that support Android apps means more chances for developers to have their apps noticed and reach new users, which means it would be all the more useful for both the developers and for Google to have a tool which makes it easier to get apps onto Chromebooks and expand the library of available apps which are optimized for the platform.
Once Google pushes things out it looks like the emulator will be available for Windows, Mac, and Linux machines, with the emulator allowing developers to open a virtual image of Chrome OS based on x86 chipsets, and for Stable, Beta, Dev, and Canary channels of the Chrome OS platform. This also means that for now Google isn't going to be offering an ARM-based Chrome OS emulator, though it's entirely possible that it could at some point in the future. At the moment there's no mention of a release date for the Chrome OS emulator inside of the Android SDK so developers will still have to physically have Chromebooks on hand if they want to test how their apps run and view on the machines. If you're a developer though, chances are you're using the Android SDK frequently and if that's the case you'll want to be sure to update the SDK when you can, as any available updates moving forward could have the Chrome OS emulator inside of it.