Bundle main thread overscroll data with event ack messages

Bundle main thread overscroll data with event ack messages

Currently, every main thread overscroll event will trigger an overscroll
IPC notification. However, most such events occur in the context of
handling input events. For such cases, bundle the overscroll data with
the event ack.

BUG=442859, 502146
Committed: https://crrev.com/c05612bf6588fd75450b28d1e01e12493efbd409
Cr-Commit-Position: refs/heads/master@{#336293}

[jdduke (slow), 2015-06-25 18:55:55]

jdduke@chromium.org changed reviewers:
+ sievers@chromium.org

[jdduke (slow), 2015-06-25 18:55:56]

sievers@: PTAL, thanks.

As an aside, it looks like RenderWidget::OnHandleInputEvent has grown into a bit
of a monster. Everybody has plugged in bits and pieces over the years (myself
included), and it's now a complete mess. I might take a stab at cleaning it up
in the next couple weeks. Yuck.

[no sievers, 2015-06-25 22:12:54]

lgtm

[jdduke (slow), 2015-06-25 22:18:46]

Patchset #2 (id:20001) has been deleted

[jdduke (slow), 2015-06-25 22:21:06]

Patchset #2 (id:40001) has been deleted

[jdduke (slow), 2015-06-25 22:22:32]

Patchset #2 (id:60001) has been deleted

[jdduke (slow), 2015-06-25 22:22:55]

The CQ bit was checked by jdduke@chromium.org

[jdduke (slow), 2015-06-25 22:22:55]

The patchset sent to the CQ was uploaded after l-g-t-m from sievers@chromium.org
Link to the patchset: https://codereview.chromium.org/1209043002/#ps80001
(title: "Rebase")

[commit-bot: I haz the power, 2015-06-25 22:23:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1209043002/80001

[commit-bot: I haz the power, 2015-06-25 23:13:26]

Committed patchset #2 (id:80001)

[commit-bot: I haz the power, 2015-06-25 23:14:29]

Patchset 2 (id:??) landed as
https://crrev.com/c05612bf6588fd75450b28d1e01e12493efbd409
Cr-Commit-Position: refs/heads/master@{#336293}