Introduce BubbleDialogDelegateView, which extends DialogDelegateView

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 1108904f5d519fd81f1e01b398fe39f990138a55..5a13d436760781a8ad61531b17e001045d426ae8 100644
--- a/ui/views/window/dialog_client_view.h
+++ b/ui/views/window/dialog_client_view.h
@@ -61,6 +61,10 @@ class VIEWS_EXPORT DialogClientView : public ClientView,
   // ButtonListener implementation:
   void ButtonPressed(Button* sender, const ui::Event& event) override;
 
+  void set_button_row_insets(const gfx::Insets& insets) {
+    button_row_insets_ = insets;
+  }
+
  protected:
   // For testing.
   explicit DialogClientView(View* contents_view);
@@ -71,9 +75,6 @@ class VIEWS_EXPORT DialogClientView : public ClientView,
   // Create and add the extra view, if supplied by the delegate.
   void CreateExtraView();
 
-  // Creates and adds the footnote view, if supplied by the delegate.
-  void CreateFootnoteView();
-
   // View implementation.
   void ChildPreferredSizeChanged(View* child) override;
   void ChildVisibilityChanged(View* child) override;
@@ -96,6 +97,9 @@ class VIEWS_EXPORT DialogClientView : public ClientView,
   // Closes the widget.
   void Close();
 
+  // How much to inset the button row.
+  gfx::Insets button_row_insets_;
+
   // The dialog buttons.
   LabelButton* ok_button_;
   LabelButton* cancel_button_;
@@ -103,9 +107,6 @@ class VIEWS_EXPORT DialogClientView : public ClientView,
   // The extra view shown in the row of buttons; may be NULL.
   View* extra_view_;
 
-  // The footnote view shown below the buttons; may be NULL.
-  View* footnote_view_;
-
   // True if we've notified the delegate the window is closing and the delegate
   // allosed the close. In some situations it's possible to get two closes (see
   // http://crbug.com/71940). This is used to avoid notifying the delegate