Move all* protected members in RenderWidget to be private or public

All data members are moved to be private. Most methods are as well.
A few methods are virtual to be overridden by subclasses (ie
RenderWidgetFullscreenPepper), so they stay protected. And a few
accessors are added or methods moved to be public as they are actually
called from outside the class.

Things used during RenderViewImpl initialization are left in protected
as this is a temporary state and initialization is Not Addressed Here.

If only called in tests, then the power of friendship is used to access
them instead of public.

R=ajwong@chromium.org, avi@chromium.org

Bug: 419087
Change-Id: I5a215417945aca4c3725ebc6e1561a939e6816aa
Reviewed-on: https://chromium-review.googlesource.com/1144424
Commit-Queue: danakj <danakj@chromium.org>
Reviewed-by: Albert J. Wong <ajwong@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578080}
10 files changed