The reason for NPE is that callback is registered too early, so
one callback is invoked before controller is fully inited. This
cl fix it in two ways:
1. Add NPE check in refreshUi, since this method in InstalledAppDetail
is robost to NPE
2. Move the callback to the end of constructor.
Bug: 37913054
Test: RunSettingsRoboTests
Change-Id: I54b03fb51a958a8e63bfe8a7ccfda79be1fa1956
0b83954f1c