DialogClientView: Handle nested close requests gracefully.

ui/views/window/dialog_client_view.h

Index: ui/views/window/dialog_client_view.h
diff --git a/ui/views/window/dialog_client_view.h b/ui/views/window/dialog_client_view.h
index 01faf827be2b50b149051f8db97573ab99c766d3..86ed922f81d42f793a75d7cfb458e4fbd3ed7644 100644
--- a/ui/views/window/dialog_client_view.h
+++ b/ui/views/window/dialog_client_view.h
@@ -104,6 +104,10 @@ class VIEWS_EXPORT DialogClientView : public ClientView,
   // After calling this, no button row Views will be in the view hierarchy.
   void SetupViews();
 
+  // Updates |delegate_allowed_close_| using the provided |method|. If |close|
+  // is true, invokes Widget::Close() the first time the delegate allows it.
+  void CloseWithDelegateMethod(bool (DialogDelegate::*method)(), bool close);
+
   // How much to inset the button row.
   gfx::Insets button_row_insets_;
 
@@ -127,6 +131,11 @@ class VIEWS_EXPORT DialogClientView : public ClientView,
   // twice, which can have bad consequences.
   bool delegate_allowed_close_ = false;
 
+  // True while asking the delegate whether a close should occur. The delegate
+  // may perform actions that trigger a nested close query. DialogClientView
+  // ignores these nested requests, and only acts on the first on the stack.
+  bool asking_delegate_whether_to_close_ = false;
+
   // Used to prevent unnecessary or potentially harmful changes during
   // SetupLayout(). Everything will be manually updated afterwards.
   bool adding_or_removing_views_ = false;