exo: Replace fling cancel with generic zero distance scroll

exo: Replace fling cancel with generic zero distance scroll

This change will suppress all fling cancel events unless the last event
was a fling event. Also it generates a proper sequence of a scroll
event with zero distance.

BUG=590754
TEST=Fling and touch the touchpad after fling. Should stop scrolling
motion in android apps.

Review-Url: https://codereview.chromium.org/2840113002
Cr-Commit-Position: refs/heads/master@{#469403}
(cherry picked from commit 2df8c3016f045d03ac10f347792d65809268c980)

Review-Url: https://codereview.chromium.org/2881333002 .
Cr-Commit-Position: refs/branch-heads/3071@{#574}
Cr-Branched-From: a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed: https://chromium.googlesource.com/chromium/src/+/699ff5cea381bdfe997f1528e2da7e303f703207

[denniskempin (chromium), 2017-05-16 04:33:32]

Description was changed from

==========
exo: Replace fling cancel with generic zero distance scroll

This change will suppress all fling cancel events unless the last event
was a fling event. Also it generates a proper sequence of a scroll
event with zero distance.

BUG=590754
TEST=Fling and touch the touchpad after fling. Should stop scrolling
motion in android apps.

Review-Url: https://codereview.chromium.org/2840113002
Cr-Commit-Position: refs/heads/master@{#469403}
(cherry picked from commit 2df8c3016f045d03ac10f347792d65809268c980)
==========

to

==========
exo: Replace fling cancel with generic zero distance scroll

This change will suppress all fling cancel events unless the last event
was a fling event. Also it generates a proper sequence of a scroll
event with zero distance.

BUG=590754
TEST=Fling and touch the touchpad after fling. Should stop scrolling
motion in android apps.

Review-Url: https://codereview.chromium.org/2840113002
Cr-Commit-Position: refs/heads/master@{#469403}
(cherry picked from commit 2df8c3016f045d03ac10f347792d65809268c980)

Review-Url: https://codereview.chromium.org/2881333002 .
Cr-Commit-Position: refs/branch-heads/3071@{#574}
Cr-Branched-From:
a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed:
https://chromium.googlesource.com/chromium/src/+/699ff5cea381bdfe997f1528e2da...
==========

[denniskempin (chromium), 2017-05-16 04:33:33]

Committed patchset #1 (id:1) manually as
699ff5cea381bdfe997f1528e2da7e303f703207.