Require explicit selection of traits for LazyInstance

extensions/browser/browser_context_keyed_api_factory.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef EXTENSIONS_BROWSER_BROWSER_CONTEXT_KEYED_API_FACTORY_H_
 #define EXTENSIONS_BROWSER_BROWSER_CONTEXT_KEYED_API_FACTORY_H_
 
 #include "base/macros.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
@@ skipping 38 matching lines @@
   // initialized in a header file).
   //
   // In the header file, declare GetFactoryInstance(), e.g.:
   //   class HistoryAPI {
   //   ...
   //    public:
   //     static BrowserContextKeyedAPIFactory<HistoryAPI>* GetFactoryInstance();
   //   };
   //
   // In the cc file, provide the implementation, e.g.:
-  //   static base::LazyInstance<BrowserContextKeyedAPIFactory<HistoryAPI> >
-  //   g_factory = LAZY_INSTANCE_INITIALIZER;
+  //   static base::LazyInstance<BrowserContextKeyedAPIFactory<HistoryAPI>>::
+  //      DestructorAtExit g_factory = LAZY_INSTANCE_INITIALIZER;
   //
   //   // static
   //   BrowserContextKeyedAPIFactory<HistoryAPI>*
   //   HistoryAPI::GetFactoryInstance() {
   //     return g_factory.Pointer();
   //   }
 };
 
 // A template for factories for KeyedServices that manage extension APIs. T is
 // a KeyedService that uses this factory template instead of its own separate
@@ skipping 62 matching lines @@
   bool ServiceIsNULLWhileTesting() const override {
     return T::kServiceIsNULLWhileTesting;
   }
 
   DISALLOW_COPY_AND_ASSIGN(BrowserContextKeyedAPIFactory);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_BROWSER_CONTEXT_KEYED_API_FACTORY_H_