Fixes bug where shelf items could be added for children windows

ash/common/shelf/shelf_window_watcher.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/common/shelf/shelf_window_watcher.h"
 
 #include <memory>
 #include <utility>
 
 #include "ash/common/shelf/shelf_constants.h"
@@ skipping 82 matching lines @@
 }
 
 void ShelfWindowWatcher::UserWindowObserver::OnWindowDestroying(
     WmWindow* window) {
   window_watcher_->OnUserWindowDestroying(window);
 }
 
 void ShelfWindowWatcher::UserWindowObserver::OnWindowVisibilityChanged(
     WmWindow* window,
     bool visible) {
+  // OnWindowVisibilityChanged() is called for descendants too. We only care
+  // about changes to the visibility of windows we know about.
+  if (!window_watcher_->observed_user_windows_.IsObserving(window))
+    return;
+
   // The tooltip behavior for panel windows depends on the panel visibility.
   window_watcher_->OnUserWindowPropertyChanged(window);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 
 ShelfWindowWatcher::ShelfWindowWatcher(ShelfModel* model)
     : model_(model),
       container_window_observer_(this),
       user_window_observer_(this),
@@ skipping 112 matching lines @@
     observed_container_windows_.Add(panel_container);
 }
 
 void ShelfWindowWatcher::OnDisplayRemoved(const display::Display& old_display) {
 }
 
 void ShelfWindowWatcher::OnDisplayMetricsChanged(const display::Display&,
                                                  uint32_t) {}
 
 }  // namespace ash