Clean up parameterization of cc/content scroll elasticity
Specify enabling elastic overscroll as a parameter to the compositor.
Use this parameter to determine if the LayerTreeHostImpl (as an
InputHandler) will create a ScrollElasticityHelper. The existence of
a ScrollElasticityHelper to determine if the InputHandlerProxy will
create an InputScrollElasticityController.
This is in preparation from changing this from an enable flag to
disable flag.
BUG=133097
Review URL: https://codereview.chromium.org/797173005
Cr-Commit-Position: refs/heads/master@{#309737}
13 files changed
