mac: Allows extensions to hide the bookmark page menu item.

The hidden property of the NSMenuItem is dynamically updated in
validateUserInterfaceItem:. That's not the intended purpose of the method, but
that's already how menu_controller/menu_model update the visibility of menu
items. validateUserInterfaceItem: is also called when a user attempts to invoke
the menu item with an accelerator, so this method will also allow/prevent users
from using an accelerator for the menu item.

This CL also hooks up the Cocoa logic for showing browser/page action popups
when a user selects the "bookmark this page" menu item.

BUG=342484

Review URL: https://codereview.chromium.org/161293002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253888 0039d316-1c4b-4281-b951-d872f2087c98
Lost trace-viewer while moving bootstrap_deps.

crrev.com/253795 lost the change in crrev.com/253658.

BUG=None
TEST=trybot
NOTRY=True

Review URL: https://codereview.chromium.org/183573002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253889 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253888
SVN changes up to revision 253889