Correct bottom overscroll in VariableHeightScrollable

Correct bottom overscroll in VariableHeightScrollable

Also updated the createDefaultScrollSimulation()
springConstant and drag parameters to make
non-overscroll fling scrolls slowdown faster and
overscrolls snap back into place a little more
snappily.

R=abarth@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/75d1543ef716601fb63daf254ae2428091cd1dd5

[hansmuller, 2015-07-14 19:02:55]

hansmuller@chromium.org changed reviewers:
+ hansmuller@chromium.org

[hansmuller, 2015-07-14 19:02:55]

PTAL

[abarth-chromium, 2015-07-14 19:09:32]

abarth@chromium.org changed reviewers:
+ abarth@chromium.org

[abarth-chromium, 2015-07-14 19:09:33]

lgtm

[Chinmay, 2015-07-14 20:59:08]

chinmaygarde@google.com changed reviewers:
+ chinmaygarde@google.com

[Chinmay, 2015-07-14 20:59:08]

https://codereview.chromium.org/1241733002/diff/1/sky/sdk/lib/widgets/scrolla...
File sky/sdk/lib/widgets/scrollable.dart (right):

https://codereview.chromium.org/1241733002/diff/1/sky/sdk/lib/widgets/scrolla...
sky/sdk/lib/widgets/scrollable.dart:17: // eventVelocity is pixels/second,
config min,max limits are pixels/ms
I am not sure why we do this at all. The input event from the platform returns
the velocity in pixels/second. We convert to pixels/ms here and then back to
pixels/second in the bounded behavior. The two conversions are redundant.

[hansmuller, 2015-07-14 22:35:29]

On 2015/07/14 20:59:08, Chinmay wrote:
>
https://codereview.chromium.org/1241733002/diff/1/sky/sdk/lib/widgets/scrolla...
> File sky/sdk/lib/widgets/scrollable.dart (right):
> 
>
https://codereview.chromium.org/1241733002/diff/1/sky/sdk/lib/widgets/scrolla...
> sky/sdk/lib/widgets/scrollable.dart:17: // eventVelocity is pixels/second,
> config min,max limits are pixels/ms
> I am not sure why we do this at all. The input event from the platform returns
> the velocity in pixels/second. We convert to pixels/ms here and then back to
> pixels/second in the bounded behavior. The two conversions are redundant.

I think that all of the time parameters in sdk/lib/theme/view_configuration.dart
are in ms. We could convert them to seconds or to const Durations.

[hansmuller1, 2015-07-14 22:37:02]

Committed patchset #2 (id:20001) manually as
75d1543ef716601fb63daf254ae2428091cd1dd5 (presubmit successful).