Add a scrollbar to sky-scrollable

Add a scrollbar to sky-scrollable

Ideally the scrollbar would animate out when you stop scrolling, but we're not
quite that good yet.

R=ojan@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/c9516ee0334fa0e7f5ddc59768a62e5f315a32f5

[ojan, 2015-01-27 05:32:25]

lgtm

https://codereview.chromium.org/882583002/diff/1/sky/framework/sky-scrollable...
File sky/framework/sky-scrollable.sky (right):

https://codereview.chromium.org/882583002/diff/1/sky/framework/sky-scrollable...
sky/framework/sky-scrollable.sky:61: // TODO(abarth): Can we get these values
without forcing a synchronous layout?
We should add apis that give you stale values and remove these ones. Or we could
just make these return stale values. In either case, we'll want a method to
force a layout too probably?

https://codereview.chromium.org/882583002/diff/1/sky/framework/sky-scrollable...
sky/framework/sky-scrollable.sky:75: this.vbar_.style.height = heightPercent +
'%';
This won't work if the scrollable's height is auto. I guess you can't get a
scrollbar in that case anyways?

[abarth-chromium, 2015-01-27 05:36:39]

https://codereview.chromium.org/882583002/diff/1/sky/framework/sky-scrollable...
File sky/framework/sky-scrollable.sky (right):

https://codereview.chromium.org/882583002/diff/1/sky/framework/sky-scrollable...
sky/framework/sky-scrollable.sky:61: // TODO(abarth): Can we get these values
without forcing a synchronous layout?
On 2015/01/27 at 05:32:25, ojan wrote:
> We should add apis that give you stale values and remove these ones. Or we
could just make these return stale values. In either case, we'll want a method
to force a layout too probably?

Yeah, it seems fine to use stale values here.  I also need some sort of
notification for when the layout has changed because I need to clamp the
scrollOffset again.

https://codereview.chromium.org/882583002/diff/1/sky/framework/sky-scrollable...
sky/framework/sky-scrollable.sky:61: // TODO(abarth): Can we get these values
without forcing a synchronous layout?
On 2015/01/27 at 05:32:25, ojan wrote:
> We should add apis that give you stale values and remove these ones. Or we
could just make these return stale values. In either case, we'll want a method
to force a layout too probably?

Yeah, it seems fine to use stale values here.  I also need some sort of
notification for when the layout has changed because I need to clamp the
scrollOffset again.

https://codereview.chromium.org/882583002/diff/1/sky/framework/sky-scrollable...
sky/framework/sky-scrollable.sky:75: this.vbar_.style.height = heightPercent +
'%';
On 2015/01/27 at 05:32:25, ojan wrote:
> This won't work if the scrollable's height is auto. I guess you can't get a
scrollbar in that case anyways?

Yeah.  This should work as long as you don't change from being a fixed height to
being auto, but the whole thing gets screwed up when you change layout anyway.

[abarth-chromium, 2015-01-27 05:37:28]

Committed patchset #1 (id:1) manually as
c9516ee0334fa0e7f5ddc59768a62e5f315a32f5 (presubmit successful).