Incorrect warnings about screen density vs resolution appear to be shown

While configuring a Galaxy Nexus-like emulator, I got this error message:
"WXGA800 resolution with density of 320dpi.. are you sure?"

The resolution WXGA800 is 1280x800, which is similar to the Galaxy Nexus which definitely has a 320dpi screen. I guess the "algorithm" for deciding which densities make sense was possibly not updated when xhdpi was added.

We should probably also add automated tests for this.