mash: Convert FocusCycler to wm common types and move to //ash/common

ash/mus/bridge/wm_window_mus.cc

Index: ash/mus/bridge/wm_window_mus.cc
diff --git a/ash/mus/bridge/wm_window_mus.cc b/ash/mus/bridge/wm_window_mus.cc
index 5c748e7cce5eaa9c2ced1d7a213a987e917ff9c9..fdaba31fbc1cc8b36f0c3b8b29befe8369d1ba21 100644
--- a/ash/mus/bridge/wm_window_mus.cc
+++ b/ash/mus/bridge/wm_window_mus.cc
@@ -571,6 +571,14 @@ void WmWindowMus::Show() {
   window_->SetVisible(true);
 }
 
+views::Widget* WmWindowMus::GetWidget() {
+  // Don't return the window frame widget for an embedded window.
+  if (widget_creation_type_ == WidgetCreationType::FOR_CLIENT)
+    return nullptr;
+
+  return widget_;
+}
+
 void WmWindowMus::CloseWidget() {
   DCHECK(widget_);
   // Allow the client to service the close request for remote widgets.