Note to blink-dev as FYI:
https://groups.google.com/a/chromium.org/d/msg/blink-dev/MWF549MZoCU/6-WeDvcPAgAJ
Notes on high level approach thoughts from in person discussion with szager@:
1) Make Widget::m_parent be type Member<FrameView>
2) Add m_childPlugins, m_childScrollbars to FrameView.
3) Remove Widget inheritance from PluginView and Scrollbar.
4) Remove Widget inheritance from FrameView.
...
N) Remove m_frame from FrameView, delegate to LayoutView
- Is FrameView::location() ever non-zero?
N+1) Cull extraneous methods from FrameView.
Comment 1 by wkorman@chromium.org
, Aug 12 2016