Move Extension into extensions namespace

chrome/browser/chromeos/kiosk_mode/kiosk_mode_screensaver.h

Index: chrome/browser/chromeos/kiosk_mode/kiosk_mode_screensaver.h
diff --git a/chrome/browser/chromeos/kiosk_mode/kiosk_mode_screensaver.h b/chrome/browser/chromeos/kiosk_mode/kiosk_mode_screensaver.h
index 449539f5bef8f93099d041ce44fc90e9e5b3ec81..701c18b4c3d562f964118567c73a08aff80fff1b 100644
--- a/chrome/browser/chromeos/kiosk_mode/kiosk_mode_screensaver.h
+++ b/chrome/browser/chromeos/kiosk_mode/kiosk_mode_screensaver.h
@@ -13,9 +13,12 @@
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 
-class Extension;
 class Profile;
 
+namespace extensions {
+class Extension;
+}
+
 namespace chromeos {
 
 class KioskModeScreensaver : public PowerManagerClient::Observer,
@@ -45,7 +48,7 @@ class KioskModeScreensaver : public PowerManagerClient::Observer,
 
   // Called back on the UI thread to Setup the screensaver with the now unpacked
   // and loaded extension.
-  void SetupScreensaver(scoped_refptr<Extension> extension,
+  void SetupScreensaver(scoped_refptr<extensions::Extension> extension,
                         Profile* default_profile,
                         const FilePath& extension_base_path);