views-desktop: Add the desktop-window as an observer for a widget when it gets added to the desktop.

views/desktop/desktop_window_view.cc

Index: views/desktop/desktop_window_view.cc
diff --git a/views/desktop/desktop_window_view.cc b/views/desktop/desktop_window_view.cc
index 3668c25f4e0e5b2d6288f8cc9f4f6c1cf0dac7ca..95aa1598e836e17a2d076632bdf2c76a97b3aa3b 100644
--- a/views/desktop/desktop_window_view.cc
+++ b/views/desktop/desktop_window_view.cc
@@ -176,8 +176,14 @@ void DesktopWindowView::ViewHierarchyChanged(
     bool is_add, View* parent, View* child) {
   if (!is_add &&
       active_native_widget_ &&
-      active_native_widget_->GetView() == child)
+      active_native_widget_->GetView() == child) {
     active_native_widget_ = NULL;
+  } else if (child->GetClassName() ==
+      internal::NativeWidgetView::kViewClassName) {
+    internal::NativeWidgetView* native_widget_view =
+        static_cast<internal::NativeWidgetView*>(child);
+    native_widget_view->GetAssociatedWidget()->AddObserver(this);

[sky, 2011/08/17 15:49:12]

Shouldn't you only do this during an add? And shouldn't you remove the observer
at some point?

[sadrul, 2011/08/17 15:54:25]

Indeed. I did that in a subsequent CL.
That doesn't seem to be necessary [at the moment?] since we would remove the
observer when the widget is being destroyed, at which point it doesn't matter
even if we don't remove the observer since the destroyed widget will not trigger
any of the callbacks.

+  }
 }
 
 ////////////////////////////////////////////////////////////////////////////////