Unregister ImeInsetsSourceConsumer when focus lost

ImeInsetsSourceConsumer was not unregistered when focus lost, it
was still references by InputMethodManager. So, the last activity
in the process won’t be GCed even though it has been destroyed.

Bug: 130216346
Test: atest ImeInsetsSourceConsumerTest
Change-Id: Ida19411d8361180692e7de7e012d2cd3b431fa9f
2 files changed