This guard blocks main loop.

And I've been told that by design the main thread doesn't need to be
aware of the rendering threads, so no need to take mutex here.

Change-Id: I78ec348ccc28dd67284ecdfccebb915cc1942fa8
Some cleanup on Timer.

Use a different name for handler as 'updateTimer' is also used as
a method name within the same class.  Also no need to set the interval
repeatedly & no need to stop the timer when it times out.

Change-Id: I430bc26b945d179c87310eaefd9d94986192841c