Remove touch scroll chaining from main thread scrolling.

Remove touch scroll chaining from main thread scrolling.

This leaves a bunch of potential cleanup, but we'll see whether or not
we want to stick with this before performing it.

BUG=526462
Committed: https://crrev.com/20e1ede5e6eb73dac71b026a8d76da195048145a
Cr-Commit-Position: refs/heads/master@{#351351}

[tdresser, 2015-09-03 18:08:53]

tdresser@chromium.org changed reviewers:
+ rbyers@chromium.org

[tdresser, 2015-09-03 18:08:53]

This appears to be enough for the main thread case.

See https://codereview.chromium.org/1306193006/ for the compositor side.

[Rick Byers, 2015-09-03 19:55:10]

Nit: BUG # is wrong
Nit: Please update subject / description to clarify that this impacts only
touchscreen scrolling.

LGTM with nits

https://codereview.chromium.org/1320543006/diff/1/LayoutTests/fast/events/tou...
File LayoutTests/fast/events/touch/gesture/touch-gesture-scroll-listbox.html
(right):

https://codereview.chromium.org/1320543006/diff/1/LayoutTests/fast/events/tou...
LayoutTests/fast/events/touch/gesture/touch-gesture-scroll-listbox.html:119:
debug("Gesture scrolling list past the end shouldn't scroll container div");
For cases like this, do we / should we have tests that verify that if you stop
the gesture and start again, now it does scroll the container?

[tdresser, 2015-09-09 13:47:06]

I've added a bit more test coverage. This is currently failing the scroll
customization tests - I'll make sure to fix them before landing.

[Rick Byers, 2015-09-25 16:46:26]

Still LGTM

[tdresser, 2015-09-29 16:46:55]

The CQ bit was checked by tdresser@chromium.org

[tdresser, 2015-09-29 16:46:56]

The patchset sent to the CQ was uploaded after l-g-t-m from rbyers@chromium.org
Link to the patchset: https://codereview.chromium.org/1320543006/#ps60001
(title: "Fix silly mistake in mac expectations.")

[commit-bot: I haz the power, 2015-09-29 16:47:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1320543006/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1320543006/60001

[commit-bot: I haz the power, 2015-09-29 18:06:15]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-09-29 18:07:00]

Patchset 4 (id:??) landed as
https://crrev.com/20e1ede5e6eb73dac71b026a8d76da195048145a
Cr-Commit-Position: refs/heads/master@{#351351}