So, +Android Police is basically going through the cardboard boxes stored in the Android team’s garage labeled OLD PHOTOS, COLLEGE NOTES, and WORKOUT GEAR.

As JJ Abrams will tell you, the Mystery Box should usually stay shut, but it's worth explaining this little bit of magic:

"""
System UI also houses image files of the red Jelly Bean in various states of construction. These are named "readbean[0-2]", and "redbeanandroid". These guys are probably used for the Bean Flicker Easter egg, but the interesting thing is that these are the only colors.
"""

The red bean is the only one we need. The final colors are chosen at random and chroma keyed using a ColorMatrixColorFilter:

https://github.com/android/platform_frameworks_base/blob/master/packages/SystemUI/src/com/android/systemui/BeanBag.java#L184
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