ApplicationManager: Use callback to get notified on application shutdown.

shell/application_manager/application_manager_unittest.cc

Index: shell/application_manager/application_manager_unittest.cc
diff --git a/shell/application_manager/application_manager_unittest.cc b/shell/application_manager/application_manager_unittest.cc
index 1683ab8252d9f7b301193d2eb2732ae2e8498665..af023841e34b50162eaed3cb5b56c136fb6972eb 100644
--- a/shell/application_manager/application_manager_unittest.cc
+++ b/shell/application_manager/application_manager_unittest.cc
@@ -403,8 +403,6 @@ class TestDelegate : public ApplicationManager::Delegate {
     return mapped_url;
   }
 
-  void OnApplicationError(const GURL& url) override {}
-
  private:
   std::map<GURL, GURL> mappings_;
 };