Disallowing shelf changes via drag & drop if the enterprise profile does not allow changes

ash/launcher/launcher_delegate.h

Index: ash/launcher/launcher_delegate.h
diff --git a/ash/launcher/launcher_delegate.h b/ash/launcher/launcher_delegate.h
index db69bab14d5c268b2293aaa60865fa5f048d7a6e..06e044552aa9aaaf7c332edfa0c8e864cd7bc35d 100644
--- a/ash/launcher/launcher_delegate.h
+++ b/ash/launcher/launcher_delegate.h
@@ -45,6 +45,10 @@ class ASH_EXPORT LauncherDelegate {
   // Check if the app with |app_id_| is pinned to the launcher.
   virtual bool IsAppPinned(const std::string& app_id) = 0;
 
+  // Checks whether the user is allowed to pin/unpin apps. Pinning may be
+  // disallowed by policy in case there is a pre-defined set of pinned apps.
+  virtual bool CanPin() const = 0;
+
   // Unpins app item with |app_id|.
   virtual void UnpinAppWithID(const std::string& app_id) = 0;
 };