Move ExtensionSystem into extensions namespace

chrome/browser/extensions/extension_system_factory.h

Index: chrome/browser/extensions/extension_system_factory.h
diff --git a/chrome/browser/extensions/extension_system_factory.h b/chrome/browser/extensions/extension_system_factory.h
index a6c0c9eb51f40571fd7321ffea18c2049432e0e2..6006ff580281c7da08866420f88fdf6fd764b13d 100644
--- a/chrome/browser/extensions/extension_system_factory.h
+++ b/chrome/browser/extensions/extension_system_factory.h
@@ -10,15 +10,18 @@
 #include "chrome/browser/extensions/extension_system.h"
 #include "chrome/browser/profiles/profile_keyed_service_factory.h"
 
-class ExtensionSystem;
 class Profile;
 class ProfileKeyedService;
 
+namespace extensions {
+class ExtensionSystem;
+
 // ProfileKeyedServiceFactory for ExtensionSystemImpl::Shared.
 // Should not be used except by ExtensionSystem(Factory).
 class ExtensionSystemSharedFactory : public ProfileKeyedServiceFactory {
  public:
-  static ExtensionSystemImpl::Shared* GetForProfile(Profile* profile);
+  static ExtensionSystemImpl::Shared* GetForProfile(
+      Profile* profile);
 
   static ExtensionSystemSharedFactory* GetInstance();
 
@@ -53,4 +56,6 @@ class ExtensionSystemFactory : public ProfileKeyedServiceFactory {
   virtual bool ServiceIsCreatedWithProfile() OVERRIDE;
 };
 
+}  // namespace extensions
+
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_SYSTEM_FACTORY_H_