Add support for xxhdpi and xxxhdpi when injecting a skin dpi.

Cherrypicked from AOSP (7703f5500464e18216ed77291ef70608ec6b59d2)

Change-Id: I5c89b33ac317b804abb88a7f29faf51809dda1d2
Merge tag 'android-4.4.3_r1' into HEAD

Android 4.4.3 release 1