Seem UBSAN doesn't like my forced reinterpret_cast to set the Idles Link in the Timer class. Now there are two possible solution: 1. convert all (DECL|IMPL).*_LINK call sites to use a Timer* or 2. split the inheritance of Idle from Timer again to maintain different Link<>s and move all common code into a TimerBase. While the 1st is more correct, the 2nd has a better indicator for Idles. This implements the first solution. And while at it, this also converts all call sites of SetTimeoutHdl and SetIdleHdl to SetInvokeHandler and gets rid of some local Link objects, which are just passed to the SetInvokeHandler call. It also introduces ClearInvokeHandler() and replaces the respective call sites of SetInvokeHandler( Link<Timer *, void>() ). Change-Id: I40c4167b1493997b7f136add4dad2f4ff5504b69