GitLab

Plumb views::WidgetDelegate::ShouldShowWindowTitle to the ws host frame.
Move prop to aura/client for MusClient and DesktopWindowTreeHostMus.
Make the KSV's delegate return false for ShouldShowWindowTitle.

Based on Scott's CL (PS1 matches crrev.com/c/1112587 PS4)

BUG=854324
TEST=covered by tests; No title in Chrome OS KSV (Ctrl-Alt-/)

Change-Id: I190c8245edbb310a1f03f6ec6ad318b325be04bc
Reviewed-on: https://chromium-review.googlesource.com/1113938
Commit-Queue: Michael Wasserman <msw@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#571300}