GitLab

ArcCustomTabView was the lone implementation of this abstract base.
Merge the two classes and simplify the construction to happen directly,
rather than through a factory method.

Further simplify the class by making it not be a View override.
ArcCustomTabView didn't do anything related to being a View other than
call GetWidget(), which it can just as easily call on (what was) its
child NativeViewHost.  Now that view is made a direct child of the
widget ContentsView, without the ArcCustomTabView in between.  For now,
lifetimes stay the same -- the NativeViewHost becomes
set_owned_by_client() instead of |this| in order to preserve the
property that the custom tab and its |host_| are deleted together,
irrespective of the lifetime of the widget ContentsView.

Bug: none
Change-Id: I921189cf74b63cc34d3789332e1b53a627e83602
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2225493Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Yusuke Sato <yusukes@chromium.org>
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#774344}