Move UserScript and related into extensions namespace

chrome/browser/extensions/extension_system.h

Index: chrome/browser/extensions/extension_system.h
diff --git a/chrome/browser/extensions/extension_system.h b/chrome/browser/extensions/extension_system.h
index c84f0abefd8f1c81b5801517548a3f9a4570ae51..ecfd00611e44bf3389927e847e0e2a6b8119324f 100644
--- a/chrome/browser/extensions/extension_system.h
+++ b/chrome/browser/extensions/extension_system.h
@@ -20,7 +20,6 @@ class ExtensionNavigationObserver;
 class ExtensionProcessManager;
 class ExtensionService;
 class Profile;
-class UserScriptMaster;
 
 namespace extensions {
 class AlarmManager;
@@ -31,6 +30,7 @@ class LazyBackgroundTaskQueue;
 class ManagementPolicy;
 class RulesRegistryService;
 class StateStore;
+class UserScriptMaster;
 
 // The ExtensionSystem manages the creation and destruction of services
 // related to extensions. Most objects are shared between normal
@@ -66,7 +66,7 @@ class ExtensionSystem : public ProfileKeyedService {
   virtual ExtensionDevToolsManager* devtools_manager() = 0;
 
   // The UserScriptMaster is created at startup.
-  virtual UserScriptMaster* user_script_master() = 0;
+  virtual extensions::UserScriptMaster* user_script_master() = 0;
 
   // The ExtensionProcessManager is created at startup.
   virtual ExtensionProcessManager* process_manager() = 0;