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 efab7e7474ec1dc8a08c9b43060d191bdd01c926..09b0c06e3218993abc411a863ece7f91f161e699 100644
--- a/ash/mus/bridge/wm_window_mus.cc
+++ b/ash/mus/bridge/wm_window_mus.cc
@@ -575,6 +575,14 @@ void WmWindowMus::Show() {
   window_->SetVisible(true);
 }
 
+views::Widget* WmWindowMus::GetInternalWidget() {
+  // Don't return the window frame widget for an embedded client 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.