Gracefully handle a disconnected popup menu client on disposing open popup.

If the client of a PopupMenu disconnects itself before destructing a
currently open popup menu (and its page), handle the fact that the client
is not reachable for notifications.

R=keishi,haraken
BUG=457383

Review URL: https://codereview.chromium.org/920433002

git-svn-id: svn://svn.chromium.org/blink/trunk@189983 bbb929c8-8fbe-4397-9dbb-9b2b20218538
5 files changed
tree: a6c663c00ca3ebd81ac6d4ffd1cc000d844874b5
  1. third_party/