Scrollable TabBar Version 1 - support for flinging
Scrollable TabBar Version 1 - support for flinging

As far as I can tell, Material TabBars are not supposed
to overscroll/bounce. The new TabBarScrollBehavior
class supports fling, but it doesn't overscroll/bounce.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1215713009.

jianglu/mojo,afandria/mojo,afandria/mojo,jianglu/mojo,chinmaygarde/mojo,afandria/mojo,afandria/mojo,chinmaygarde/mojo,chinmaygarde/mojo,afandria/mojo,afandria/mojo,jianglu/mojo,chinmaygarde/mojo,jianglu/mojo,afandria/mojo,chinmaygarde/mojo,jianglu/mojo,jianglu/mojo,jianglu/mojo,afandria/mojo,chinmaygarde/mojo,chinmaygarde/mojo,chinmaygarde/mojo,jianglu/mojo,chinmaygarde/mojo