If a dialog is shown, drop fullscreen.

BUG=875066, 817809, 792876, 812769, 813815
TEST=included

Change-Id: Ic3d697fa3c4b01f5d7fea77391857177ada660db
Reviewed-on: https://chromium-review.googlesource.com/1185208
Reviewed-by: Sidney San Martín <sdy@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586418}
bool Browser::ShouldStartShutdown() const {
  if (IsBrowserClosing())
    return false;

  const size_t closing_browsers_count =
      BrowserList::GetInstance()->currently_closing_browsers().size();
  return BrowserList::GetInstance()->size() == closing_browsers_count + 1u;
}

bool Browser::ShouldStartShutdown() const {
  if (IsBrowserClosing())
    return false;

  const size_t closing_browsers_count =
      BrowserList::GetInstance()->currently_closing_browsers().size();
  return BrowserList::GetInstance()->size() == closing_browsers_count + 1u;
}
