Fixed dangling DC controller

Instead of creating a DcController everytime, we reuse
the existing one and just register for events created.
This essentially reverts the behavior of ag/11549405,
which should not happen after ag/13310488.

Test: Manual
Bug: 176458078
Merged-In: I6a74fcaf60f66e49a389ae9840a925dc789940f1
Change-Id: I6a74fcaf60f66e49a389ae9840a925dc789940f1
(cherry picked from commit b2a68cca)