Linux UI: Add IsVisibleOnAllWorkspaces()

ui/views/widget/native_widget_mac.mm

Index: ui/views/widget/native_widget_mac.mm
diff --git a/ui/views/widget/native_widget_mac.mm b/ui/views/widget/native_widget_mac.mm
index c6425cd244d3cc4473700c1be9164c86b56e1319..00e5f50a021ed34171a1c6283b545a9bce88556b 100644
--- a/ui/views/widget/native_widget_mac.mm
+++ b/ui/views/widget/native_widget_mac.mm
@@ -463,6 +463,10 @@ void NativeWidgetMac::SetVisibleOnAllWorkspaces(bool always_visible) {
   gfx::SetNSWindowVisibleOnAllWorkspaces(GetNativeWindow(), always_visible);
 }
 
+bool NativeWidgetMac::IsVisibleOnAllWorkspaces() const {
+  return false;
+}
+
 void NativeWidgetMac::Maximize() {
   NOTIMPLEMENTED();  // See IsMaximized().
 }