Provide hook to abort dialog cancellation, disable cancellation during install.

ui/views/window/dialog_client_view.cc

Index: ui/views/window/dialog_client_view.cc
diff --git a/ui/views/window/dialog_client_view.cc b/ui/views/window/dialog_client_view.cc
index 1c289d3140ebfe7f36a03f6d80ab0430bd09d386..8116c502ba112a5f3137b6e3b472b5319c49d935 100644
--- a/ui/views/window/dialog_client_view.cc
+++ b/ui/views/window/dialog_client_view.cc
@@ -263,6 +263,8 @@ bool DialogClientView::CanClose() {
     close = dd->Cancel();
   else if (buttons & ui::DIALOG_BUTTON_OK)
     close = dd->Accept(true);
+  else if (buttons == ui::DIALOG_BUTTON_NONE)

[sky, 2012/09/24 13:50:42]

combine this with 262.
Also, update the description in DialogDelegate::Cancel(). And, did you look at
existing subclasses to make sure this isn't going to cause problems?

[groby-ooo-7-16, 2012/09/25 17:27:11]

Done.

Checked existing dialogs, and three use DIALOG_BUTTON_NONE (besides
WebIntentPicker):
AboutIPCDialog
TaskManagerView
IdleLogoutDialogView

None of these override Cancel(), so default behavior is observed -> close is set
to true. Same as it was before the change.

+    close = dd->Cancel();
   notified_delegate_ = close;
   return close;
 }