FW: Custom Scroll mod [1/2]

ported from -> scotthartbti/android_frameworks_base@423f797

ported/modified from https://gerrit.omnirom.org/#/c/4251/

originally written by Yanuar Harry <ai.the.smarties.physics@gmail.com>

PS2: update author & message
PS3: fix derp private --> public

Change-Id: I0be00d138a4612c11154f35a8cfdfaca65880b51