Move Extension into extensions namespace

chrome/browser/ui/webui/options2/search_engine_manager_handler2.h

Index: chrome/browser/ui/webui/options2/search_engine_manager_handler2.h
diff --git a/chrome/browser/ui/webui/options2/search_engine_manager_handler2.h b/chrome/browser/ui/webui/options2/search_engine_manager_handler2.h
index 95af05ed43ecdf5e7197272786ac96e10a1e9857..e2bddaf0e3ceaf3b0b80ed3ac8c950d73c4e5be4 100644
--- a/chrome/browser/ui/webui/options2/search_engine_manager_handler2.h
+++ b/chrome/browser/ui/webui/options2/search_engine_manager_handler2.h
@@ -9,9 +9,12 @@
 #include "chrome/browser/ui/webui/options2/options_ui2.h"
 #include "ui/base/models/table_model_observer.h"
 
-class Extension;
 class KeywordEditorController;
 
+namespace extensions {
+class Extension;
+}
+
 namespace options2 {
 
 class SearchEngineManagerHandler : public OptionsPageUIHandler,
@@ -73,7 +76,7 @@ class SearchEngineManagerHandler : public OptionsPageUIHandler,
 
   // Returns a dictionary to pass to WebUI representing the extension.
   base::DictionaryValue* CreateDictionaryForExtension(
-      const Extension& extension);
+      const extensions::Extension& extension);
 
   DISALLOW_COPY_AND_ASSIGN(SearchEngineManagerHandler);
 };