Move shelf item tooltip flag from delegate to item.

ash/common/shelf/shelf_window_watcher.cc

Index: ash/common/shelf/shelf_window_watcher.cc
diff --git a/ash/common/shelf/shelf_window_watcher.cc b/ash/common/shelf/shelf_window_watcher.cc
index 648a8060b2086a5c6f2fa454a28b307d9a249fa7..2b7ee83ed3ef85df0aea6147d76a1c56c1cbe9f3 100644
--- a/ash/common/shelf/shelf_window_watcher.cc
+++ b/ash/common/shelf/shelf_window_watcher.cc
@@ -38,6 +38,11 @@ void UpdateShelfItemForWindow(ShelfItem* item, WmWindow* window) {
   item->image = window->GetAppIcon();
   if (item->image.isNull())
     item->image = window->GetWindowIcon();
+
+  // Do not show tooltips for visible attached app panel windows.
+  item->shows_tooltip =
+      item->type != TYPE_APP_PANEL || !window->IsVisible() ||

[sky, 2016/12/08 00:38:54]

Do we always end up back in this function when the visibility changes?

[msw, 2016/12/08 20:31:36]

This was just working by chance, because minimizing/restoring (or closing)
panels seem to be the only way to change their visibility, and that was also
changing their activation. I wired up WmWindowObserver::OnVisibilityChanged to
this function. It seems like that might add some wasteful no-ops for children
and ancestors of observed user windows, but I don't know how much that really
matters, nor do I have any great ideas to avoid that.

+      !window->GetBoolProperty(WmWindowProperty::PANEL_ATTACHED);
 }
 
 }  // namespace
@@ -80,6 +85,7 @@ void ShelfWindowWatcher::UserWindowObserver::OnWindowPropertyChanged(
   if (property == WmWindowProperty::APP_ICON ||
       property == WmWindowProperty::APP_ID ||
       property == WmWindowProperty::DRAW_ATTENTION ||
+      property == WmWindowProperty::PANEL_ATTACHED ||
       property == WmWindowProperty::SHELF_ITEM_TYPE ||
       property == WmWindowProperty::WINDOW_ICON) {
     window_watcher_->OnUserWindowPropertyChanged(window);