Root cause:
App info page will load application icon and content description in
onBindViewHolder(), it will query PackageManager and UserManager many
times in scrolling. Actually these actions will become time consuming if
there is a large app list.
Solution:
To relieve the janky scrolling, cache the icon and content description
if it has been loaded once.
Bug: 156527207
Test: manual test and robotests
Change-Id: I997179834511f86b3155c7d54989a873ac8e2559
6b457d882c