mus: Let clients set the cursor of their window.

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 9b382fe6aa481fcc13cc7bd01032ece217daad20..16eff90818d4978f810cdbd56209eb7147bcacac 100644
--- a/components/mus/ws/access_policy.h
+++ b/components/mus/ws/access_policy.h
@@ -50,6 +50,9 @@ class AccessPolicy {
   virtual bool CanSetWindowTextInputState(const ServerWindow* window) const = 0;
   virtual bool CanSetFocus(const ServerWindow* window) const = 0;
   virtual bool CanSetClientArea(const ServerWindow* window) const = 0;
+  // Used for all cursor properties; which cursor should be displayed,
+  // visibility, locking, etc.
+  virtual bool CanSetCursorProperties(const ServerWindow* window) const = 0;
 
   // Returns whether the connection should notify on a hierarchy change.
   // |new_parent| and |old_parent| are initially set to the new and old parents