Makes ash/mus use RootWindowControllerCommon

ash/mus/bridge/wm_shell_mus.cc

Index: ash/mus/bridge/wm_shell_mus.cc
diff --git a/ash/mus/bridge/wm_shell_mus.cc b/ash/mus/bridge/wm_shell_mus.cc
index 8d254ee4f37ab6cd2075bf7ab50175b783a3dbf7..67fa439caf3c92ea749f7cd0ca5892a9ce3d99ee 100644
--- a/ash/mus/bridge/wm_shell_mus.cc
+++ b/ash/mus/bridge/wm_shell_mus.cc
@@ -184,8 +184,9 @@ bool WmShellMus::IsActivationParent(::mus::Window* window) {
   if (!window)
     return false;
 
-  for (size_t i = 0; i < kNumActivationContainers; ++i) {
-    if (window->local_id() == static_cast<int>(kActivationContainers[i]))
+  const int shell_window_id = WmWindowMus::Get(window)->GetShellWindowId();
+  for (size_t i = 0; i < kNumActivatableShellWindowIds; ++i) {
+    if (shell_window_id == kActivatableShellWindowIds[i])
       return true;
   }
   return false;