Fix settings crash

- This CL before, "Previously connected device" didn't
  handle dock device. If user have disconnected dock
  device will cause Settings crash.

  This CL add condition to handle dock device to avoid crash.
- Update test case.

Bug: 157653997
Bug: 167054620
Test: make -j42 RunSettingsRoboTests
Change-Id: I769cee3f589e14a993b00a0ae6ec3ddfba8ef281
Merged-In: I769cee3f589e14a993b00a0ae6ec3ddfba8ef281