All menus on aura platforms no longer use the nested message loop code path of MenuController.
On Mac non-native menus also no longer use the nested message loop. While native menus are handled vis menu_runner_impl_cocoa, which does block.
This change removes the Nested Message Loop code paths from MenuController.
Additionally some tests which specifically were for nested message loops below asynchronous menus, have been either transitioned, or removed if redundant.
TEST=views_unittests, manual testing.
BUG=557130
Review-Url: https://codereview.chromium.org/2779373002
Cr-Commit-Position: refs/heads/master@{#460818}
11 files changed
