Follow-up to "Close notification panel when user button is tapped"

The original CL just collapsed the panel. Instead, we're using the
dedicated startActivityDismissingKeyguard to make sure the Keyguard
gets properly dismissed first.

Follow-Up-To: I66ebcb66c898dfebe1d09b798f750f696c360da8
Bug: 27790403
Change-Id: I41c02221de951df885ecfb4f2869820b38410f18
1 file changed