DO NOT MERGE
DO NOT MERGE

Adopt the sloppy detection in the ScaleGestureDetector.
Try to fix the fat thumb problem.

Fix http://b/issue?id=2385061

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