Bottom browser controls position based on window height
This change has the browser controls depend on the window viewport
rather than the visible viewport when drawing. This allows for the
math to be consistent across layouts that use the controls and
fixes the toolbar swipe layout.
To facilitate this, the SceneOverlay interface was updated to
include the window and visible viewports when updating their
respective SceneLayers.
BUG=
652892
Committed:
https://crrev.com/db62741d2a98508eae38f71a1e24672d66eda2f9
Cr-Commit-Position: refs/heads/master@{#437584}