views: menu: Remove MenuMessageLoop::ShouldQuitNow
This check was added in r169118 to guard against terminating the wrong
message loop when a menu closes via MessageLoop::current()->QuitNow().
We are now using RunLoop::Quit() to terminate the menu message loop, so
this cannot happen. We can remove this check and allow menu message loops
to unwind as soon as they are able.
This change fixes some views menu DnD tests not terminating on CrOS
ozone, because ViewEventTestBase::Done() is not able to terminate both
the menu loop and its own loop robustly.
BUG=444428,446335
TEST=BookmarkBarViewTest{5,7,8} with chromeos=1 use_ozone=1 build
Review URL: https://codereview.chromium.org/
835993002
Cr-Commit-Position: refs/heads/master@{#310020}