Minor fixes for WidgetRemovalsObserver::OnWillRemoveView

ui/views/widget/widget_removals_observer.h

 // Copyright 2014 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.
 
 #ifndef UI_VIEWS_WIDGET_WIDGET_REMOVALS_OBSERVER_H_
 #define UI_VIEWS_WIDGET_WIDGET_REMOVALS_OBSERVER_H_
 
 #include "ui/views/views_export.h"
 
 namespace views {
 
 class Widget;
 class View;
 
 // |WidgetRemovalsObserver| complements |WidgetObserver| with additional
 // notifications. These include events occurring during tear down like view
 // removal. For this reason, it is recommended that subclasses not also inherit
 // from |View|.
 class VIEWS_EXPORT WidgetRemovalsObserver {
  public:
-  // Called immediately before a descendant view of |widget| is removed.
+  // Called immediately before a descendant view of |widget| is removed
+  // from this widget. Won't be called if the view is moved within the
+  // same widget, but will be called if it's moved to a different widget.
+  // Only called on the root of a view tree; it implies that all of the
+  // descendants of |view| will be removed.
   virtual void OnWillRemoveView(Widget* widget, View* view) {}
 
  protected:
   virtual ~WidgetRemovalsObserver() {}
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_WIDGET_REMOVALS_OBSERVER_H_