AI 143298: am: CL 143150 Fixed the problem where setEnabled(false) has no effect from onResume().

  The problem was that the Preference widget was reenabled when its dependency
  was in enabled state. The enabled field was basically overloaded.  The fix was
  to add an additional field to keep track of whether its dependencies were met.
  Original author: chanm
  Merged from: //branches/donutburger/...

Automated import of CL 143298