Add a non-blocking "OneShotEvent" class

chrome/browser/extensions/test_extension_system.h

Index: chrome/browser/extensions/test_extension_system.h
diff --git a/chrome/browser/extensions/test_extension_system.h b/chrome/browser/extensions/test_extension_system.h
index 78ef6f2b6ef74241f49e64bec74ff8bfda04369c..b2a49a423d5abc089eb8538dcd4e22e5323ad21c 100644
--- a/chrome/browser/extensions/test_extension_system.h
+++ b/chrome/browser/extensions/test_extension_system.h
@@ -71,6 +71,9 @@ class TestExtensionSystem : public ExtensionSystem {
       OVERRIDE;
   virtual ExtensionWarningService* warning_service() OVERRIDE;
   virtual Blacklist* blacklist() OVERRIDE;
+  virtual const AsyncEvent& ready() const OVERRIDE;
+  // Calls ready().MarkHappened().
+  void MakeReady();
 
   // Factory method for tests to use with SetTestingProfile.
   static ProfileKeyedService* Build(content::BrowserContext* profile);
@@ -93,6 +96,7 @@ class TestExtensionSystem : public ExtensionSystem {
   scoped_ptr<LocationManager> location_manager_;
   scoped_refptr<ExtensionInfoMap> info_map_;
   scoped_ptr<ApiResourceManager<Socket> > socket_manager_;
+  AsyncEvent ready_;
 };
 
 }  // namespace extensions