[oxide] enable kinetic scrolling

[Bill Filler]

we should enable kinetic scrolling like qtwebkit has so you can flick to scroll.

[Chris Coulson (chrisccoulson)]

I've not tested this, but it *should* just be a matter of setting RendererPreferences::touchscreen_fling_profile to something appropriate

[Olivier Tilloy (osomon)]

RendererPreferences::touchscreen_fling_profile is already initialized to a default value that, supposedly, generates a good default fling deceleration curve (see https://code.google.com/p/chromium/codesearch#chromium/src/content/public/common/renderer_preferences.cc).

I’ve tried playing with those values, but that doesn’t seem to make any difference, so I must be missing something to actually enable flick gestures. I’ve added kEnableSmoothScrolling to the command line switches, but that doesn’t make any difference either.

[Olivier Tilloy (osomon)]

Ok, I finally nailed where the issue lies: the timestamp of the touch event we get from Qt cannot be used as a base::TimeDelta (they probably have different time origins). As a consequence, the time variable in TouchFlingGestureCurve::apply(…) was always computing to a negative value, thus cancelling the fling.