The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform/gestures/+/9956ad407739299ace45863589296d49f416a4d6

commit 9956ad407739299ace45863589296d49f416a4d6
Author: Sean O'Brien <seobrien@google.com>
Date: Wed Feb 14 05:15:26 2018

Separate logic for finger suppression reasons

Currently, we can suppress fingers when they are either stationary or
when pressure is changing significantly.  In either case, we may
continue to send scrolls using dead reckoning from previous scrolls.
When stationary finger suppression is enabled, stationary fingers may
continue to generate scroll gestures indefinitely.

This CL makes it so stationary fingers will only send zero-length
scrolls, instead of scrolls using dead reckoning.  Fingers with
significant pressure change will still send dead reckoning scrolls.

This CL also changes the criteria for stationary finger suppression.
Before a finger was considered not stationary if the sum finger movement
from frame to frame exceeded the threshold.  This meant that a finger
which appears stationary would accrue enough small movement to pass this
threshold.

Now the difference in finger position from the first stationary moment
to now must exceed the threshold, so minor movements which cancel out
won't add up.

BUG= chromium:804515 
TEST=Test on eve, samus, and swanky. Check for regressions on touchtests suite.
CQ-DEPEND=CL:881645

Change-Id: I5195a1f0e9cbd405babbfd390a912ffa62ae2349
Reviewed-on: https://chromium-review.googlesource.com/879743
Commit-Ready: Sean O'Brien <seobrien@chromium.org>
Tested-by: Sean O'Brien <seobrien@chromium.org>
Reviewed-by: Andrew de los Reyes <adlr@chromium.org>

[modify] https://crrev.com/9956ad407739299ace45863589296d49f416a4d6/include/immediate_interpreter.h
[modify] https://crrev.com/9956ad407739299ace45863589296d49f416a4d6/src/immediate_interpreter.cc
[modify] https://crrev.com/9956ad407739299ace45863589296d49f416a4d6/src/immediate_interpreter_unittest.cc