Only report bounding box touch hit rect for non-composited scroll layers.

Compositor touch hit rects report unnecessary rects for non-composited scrolling layers

A non-composited scrolling layer will get projected to the same compositing
layer as its bounding box so to make its visualization easier don't report
m_scrollableArea->overflowRect().

BUG=337844
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=166084

[Rick Byers, 2014-01-29 17:46:23]

LGTM, this is great - thanks Zeeshan!  I'd suggest mentioning in your
description that it also makes visualization of non-composited scroll hit rects
easier.  That's the main reason we're doing it now.

The improved hit testing effectiveness is nice too, but since we don't (yet)
have a test or metric to track that it's not really the main reason we're
changing this.

+levi for OWNERS

https://codereview.chromium.org/148423004/diff/10001/LayoutTests/fast/events/...
File
LayoutTests/fast/events/touch/compositor-touch-hit-rects-non-composited-scroll-expected.txt
(right):

https://codereview.chromium.org/148423004/diff/10001/LayoutTests/fast/events/...
LayoutTests/fast/events/touch/compositor-touch-hit-rects-non-composited-scroll-expected.txt:5:
scrollContainerWithHandler: #document (13, 110, 290, 25)
I guess I didn't have a test case for this before, so (for other reviewers) it's
not easy to spot the difference in behavior here.  They key thing is that the
height of this rect is '25' where the contents of this scrollable element is
>90px tall.  Previously we'd report the 90px into the #document layer, now we
report only the scrolling container.

[leviw_travelin_and_unemployed, 2014-01-29 17:59:10]

Code change lgtm! Please copy the bug title into the description (otherwise it
won't be part of the commit message) and wrap your actual commit message to 80
columns.

[Zeeshan Qureshi, 2014-01-29 18:13:12]

Updated description.

[commit-bot: I haz the power, 2014-01-29 18:16:23]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/zeeshanq@chromium.org/148423004/10001

[commit-bot: I haz the power, 2014-01-30 06:00:23]

Commit queue rejected this change because the description was changed
between the time the change entered the commit queue and the time it
was ready to commit. You can safely check the commit box again.

[commit-bot: I haz the power, 2014-01-30 06:00:24]

CQ bit was unchecked on CL. Ignoring.

[commit-bot: I haz the power, 2014-01-30 06:01:22]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/zeeshanq@chromium.org/148423004/10001

[commit-bot: I haz the power, 2014-01-30 06:01:59]

Change committed as 166084