Dismiss action in tab modal dialogs.

ui/views/window/dialog_delegate.h

Index: ui/views/window/dialog_delegate.h
diff --git a/ui/views/window/dialog_delegate.h b/ui/views/window/dialog_delegate.h
index 7781064ba91245493b287ef170430bb4bd6de763..10bd79d65ca0d92724ca75db018912f1e265d95e 100644
--- a/ui/views/window/dialog_delegate.h
+++ b/ui/views/window/dialog_delegate.h
@@ -54,22 +54,29 @@ class VIEWS_EXPORT DialogDelegate : public ui::DialogModel,
   virtual View* CreateFootnoteView();
 
   // For Dialog boxes, if there is a "Cancel" button or no dialog button at all,
-  // this is called when the user presses the "Cancel" button or the Close
-  // button on the window or in the system menu, or presses the Esc key.
-  // This function should return true if the window can be closed after it
-  // returns, or false if it must remain open.
+  // this is called when the user presses the "Cancel" button or the Esc key.
+  // It can also be called on a dismiss action if |Dismiss| has not been
+  // overridden. This function should return true if the window can be closed
+  // after it returns, or false if it must remain open.
   virtual bool Cancel();
 
   // For Dialog boxes, this is called when the user presses the "OK" button,
-  // or the Enter key.  Can also be called on Esc key or close button
-  // presses if there is no "Cancel" button.  This function should return
-  // true if the window can be closed after it returns, or false if it must
-  // remain open.  If |window_closing| is true, it means that this handler is
+  // or the Enter key. It can also be called on a dismiss action if |Dismiss|
+  // has not been overridden. This function should return true if the window
+  // can be closed after it returns, or false if it must remain open.
+  // If |window_closing| is true, it means that this handler is
   // being called because the window is being closed (e.g.  by Window::Close)
   // and there is no Cancel handler, so Accept is being called instead.
   virtual bool Accept(bool window_closing);
   virtual bool Accept();
 
+  // For Dialog boxes, this is called when the user presses the Close button
+  // on the window or in the system menu. The default behavior is to call
+  // |Cancel| if the dialog has a "Cancel" button or no button at all, or
+  // |Accept| otherwise. This function should return true if the window can be
+  // closed after it returns, or false if it must remain open.
+  virtual bool Dismiss();
+
   // Overridden from ui::DialogModel:
   virtual base::string16 GetDialogLabel() const OVERRIDE;
   virtual base::string16 GetDialogTitle() const OVERRIDE;