Makes WindowTree take the AccessPolicy

components/mus/ws/access_policy.h

Index: components/mus/ws/access_policy.h
diff --git a/components/mus/ws/access_policy.h b/components/mus/ws/access_policy.h
index 8ba6ff63090aef112cc0cbc9f15aa2825c1b098c..be3fdc9d1a88ce0fd6e6a2cb563f8408ba49a8fc 100644
--- a/components/mus/ws/access_policy.h
+++ b/components/mus/ws/access_policy.h
@@ -14,6 +14,7 @@
 namespace mus {
 namespace ws {
 
+class AccessPolicyDelegate;
 class ServerWindow;
 
 // AccessPolicy is used by WindowTree to determine what the WindowTree is
@@ -22,6 +23,9 @@ class AccessPolicy {
  public:
   virtual ~AccessPolicy() {}
 
+  virtual void Init(ConnectionSpecificId connection_id,
+                    AccessPolicyDelegate* delegate) = 0;
+
   // Unless otherwise mentioned all arguments have been validated. That is the
   // |window| arguments are non-null unless otherwise stated (eg CanSetWindow()
   // is allowed to take a NULL window).