Don't post tasks from RulesRegistry c-tor

extensions/common/one_shot_event.h

Index: extensions/common/one_shot_event.h
diff --git a/extensions/common/one_shot_event.h b/extensions/common/one_shot_event.h
index 17ab5c88f73133954f3d1b29335bcb11435d0f8a..9baa152d2c5ce96924978c451efb4efd8bdb557e 100644
--- a/extensions/common/one_shot_event.h
+++ b/extensions/common/one_shot_event.h
@@ -35,6 +35,11 @@ namespace extensions {
 class OneShotEvent {
  public:
   OneShotEvent();
+  // Use the following constructor to create an already signaled event. This is
+  // useful if you construct the event on a different thread from where it is
+  // used, in which case it is not possible to call Signal() just after
+  // construction.
+  explicit OneShotEvent(bool signaled);
   ~OneShotEvent();
 
   // True if Signal has been called.  This function is mostly for