Replace the WAS_INSTALLED_BY_CUSTODIAN creation flag with a pref

chrome/browser/supervised_user/supervised_user_service.h

Index: chrome/browser/supervised_user/supervised_user_service.h
diff --git a/chrome/browser/supervised_user/supervised_user_service.h b/chrome/browser/supervised_user/supervised_user_service.h
index 92269767eb8768065c2bec107bbd566f2335ffa9..68ee25436f68056d05e6feda90590ca95f45f5c2 100644
--- a/chrome/browser/supervised_user/supervised_user_service.h
+++ b/chrome/browser/supervised_user/supervised_user_service.h
@@ -302,6 +302,25 @@ class SupervisedUserService : public KeyedService,
   bool MustRemainInstalled(const extensions::Extension* extension,
                            base::string16* error) const override;
 
+  // An extension can be in one of the following states:
+  //
+  // FORCED: if it is installed by the custodian.
+  // ALLOWED: Components, Themes, Default extensions ..etc
+  //    are generally allowed.  Extensions that have been approved by the
+  //    custodian are also allowed.
+  // BLOCKED: if it is not ALLOWED or FORCED
+  //    and supervised users initiated installs are disabled.
+  enum ExtensionState {
+    EXTENSION_FORCED,
+    EXTENSION_BLOCKED,
+    EXTENSION_ALLOWED
+  };
+
+  // Returns the state of an extension whether being FORCED, BLOCK, or ALLOWED
+  // from the Supervised User service's point of view.
+  ExtensionState GetExtensionState(
+      const extensions::Extension* extension) const;
+
   // Extensions helper to SetActive().
   void SetExtensionsActive();
 #endif