IMS-VT: Fix race condition

Due to race condition in VideoCallPresenter
the onUiShowing notification was being
ignored. This resulted in disabling camera
even though UI was in foreground.

Fix the issue by explicitly requesting
onUiShowing notification upon initialization.

CRs-fixed: 2006898
Change-Id: I5d827724472134723a70d3c3ec23563b6b6e7f83
2 files changed