Ensure that custom label isn't empty
Ensure that custom label isn't empty

This also changes getHiddenTvInputIds to return mutable ArrayList.

Bug: 16876078
Change-Id: Ib84a071e7a7cf390ac4f9cf69f3d8daf218d657d

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base