mash: Convert ash shelf overflow bubble to wm common types

ash/mus/bridge/wm_shelf_mus.cc

Index: ash/mus/bridge/wm_shelf_mus.cc
diff --git a/ash/mus/bridge/wm_shelf_mus.cc b/ash/mus/bridge/wm_shelf_mus.cc
index 2dcd4dbeaa8525c0bf247344b2adc82a962e1924..fc7feca02c4da7fee78acb53a5f958c23fc63c53 100644
--- a/ash/mus/bridge/wm_shelf_mus.cc
+++ b/ash/mus/bridge/wm_shelf_mus.cc
@@ -69,6 +69,15 @@ bool WmShelfMus::IsDimmed() const {
   return false;
 }
 
+bool WmShelfMus::IsShowingOverflowBubble() const {
+  NOTIMPLEMENTED();
+  return false;
+}
+
+void WmShelfMus::SchedulePaint() {
+  NOTIMPLEMENTED();
+}
+
 bool WmShelfMus::IsVisible() const {
   NOTIMPLEMENTED();
   return true;