Removes ash::mus::RootWindowController

ash/root_window_controller.h

Index: ash/root_window_controller.h
diff --git a/ash/root_window_controller.h b/ash/root_window_controller.h
index 56610f579824e732d77ccd71f7ee214f6cc66dbd..69b0c134a2704a3f11cef902f8bf98e0be80b725 100644
--- a/ash/root_window_controller.h
+++ b/ash/root_window_controller.h
@@ -67,7 +67,7 @@ class WmShelf;
 class WorkspaceController;
 
 namespace mus {
-class RootWindowController;
+class WindowManager;
 }
 
 namespace wm {
@@ -291,7 +291,7 @@ class ASH_EXPORT RootWindowController : public ShellObserver {
  private:
   // TODO(sky): remove this. Temporary during ash-mus unification.
   // http://crbug.com/671246.
-  friend class mus::RootWindowController;
+  friend class mus::WindowManager;
 
   // Creates a new RootWindowController with the specified host. Only one of
   // |ash_host| or |window_tree_host| should be specified. This takes ownership