Reland: Add an event to notify accessibility when a permissions bubble gets shown.

ui/views/bubble/bubble_delegate.cc

Index: ui/views/bubble/bubble_delegate.cc
diff --git a/ui/views/bubble/bubble_delegate.cc b/ui/views/bubble/bubble_delegate.cc
index 55ce980289149c322219d60e35222009d4ee8614..a2070c0bb21fb67ee271d5b911d5623a6f7e1271 100644
--- a/ui/views/bubble/bubble_delegate.cc
+++ b/ui/views/bubble/bubble_delegate.cc
@@ -305,6 +305,13 @@ void BubbleDelegateView::HandleVisibilityChanged(Widget* widget, bool visible) {
     else
       anchor_widget()->GetTopLevelWidget()->EnableInactiveRendering();
   }
+
+  if (widget == GetWidget() && visible) {
+    ui::AXViewState state;
+    GetAccessibleState(&state);
+    if (state.role == ui::AX_ROLE_ALERT_DIALOG)
+      NotifyAccessibilityEvent(ui::AX_EVENT_ALERT, true);
+  }
 }
 
 }  // namespace views