New implementation for ScaleGestureDetector
New implementation for ScaleGestureDetector

This solves the problems around active pointer tracking when the
caller may skip events in the MotionEvent stream and replaces the
old implementation with a much simpler algorithm.

Change-Id: I6b15a2e215cab7b9559db800fcc57374702357fc

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base