Remove unused ImplCallEvent

Change-Id: I18ef9f11adce64be7ce93b077d1703ab505918a6
ImplCallPreNotify should return bool

Change-Id: I4b25d70c1009fbc714208452c2a646161189ff24
-Werror,-Wunused-variable

Change-Id: I39d15f863f4e1fd585b03bfc5f8854fb66af3b4c
Window::PreNotify should return bool

Change-Id: Ic9903fd887f2c3fab2630ebeb20df39392177c8d