Fix memory leak. Camera application is leaking activities.

ComboPreferences.sMap (value)
-->ComboPreference (field mListeners)
-->HeadUpDisplay
-->activities

Make sure HeadUpDisplay is unregistered from ComboPreference
listener list.

bug:2949181
Change-Id: Ia0350afd6e9f23f92ce4b252a4b74709b4cd5bf7
1 file changed