Avert crash in ExtensionInstalledBubbleView::GetWindowTitle triggered

ui/views/window/dialog_delegate.cc

Index: ui/views/window/dialog_delegate.cc
diff --git a/ui/views/window/dialog_delegate.cc b/ui/views/window/dialog_delegate.cc
index d98274cde71a90871a5fd96875f70838ca61cb3f..81f636723102cb125094045070ea489f5d154ff3 100644
--- a/ui/views/window/dialog_delegate.cc
+++ b/ui/views/window/dialog_delegate.cc
@@ -255,7 +255,10 @@ View* DialogDelegateView::GetContentsView() {
 }
 
 void DialogDelegateView::GetAccessibleState(ui::AXViewState* state) {
-  state->name = GetWindowTitle();
+  // This may be called by screen readers after the window is closed.
+  // See crbug.com/648280
+  if (!GetWidget()->IsClosed())
+    state->name = GetWindowTitle();
   state->role = ui::AX_ROLE_DIALOG;
 }