am a4877aed: Merge "Updating code sample for "displaying bitmaps efficiently" training class. Changes:  -Use updated versions of ImageWorker & ImageCache from I/O 2012 app  -Use copied DiskLruCache from system (rather than custom)  -Use copied AsyncTask from system (t

* commit 'a4877aed7654e8bc7f531593f75c1ae05ef3411c':
  Updating code sample for "displaying bitmaps efficiently" training class. Changes:  -Use updated versions of ImageWorker & ImageCache from I/O 2012 app  -Use copied DiskLruCache from system (rather than custom)  -Use copied AsyncTask from system (to keep behavior consistent)  -Ensure no strict mode violations or lint errors  -Other misc bug fixes  -Move single-use static methods in Utils to corresponding class