am: 5224271
* commit '5224271f2c4f37fce92dd8d5b42ca0bc8242a30d':
Clean up docs, attrs, and APIs for PopupWindow enter/exit transitions
am: 5224271
* commit '5224271f2c4f37fce92dd8d5b42ca0bc8242a30d':
Clean up docs, attrs, and APIs for PopupWindow enter/exit transitions