chrome: Cleanup class/struct forward declarations

chrome/browser/extensions/permissions_updater.h

Index: chrome/browser/extensions/permissions_updater.h
diff --git a/chrome/browser/extensions/permissions_updater.h b/chrome/browser/extensions/permissions_updater.h
index 2bb6f8fe2f9d62149afdbffad1b3e4e0f051ed2d..e31d52a45b0d00a6e0b902b2727139cf01e13605 100644
--- a/chrome/browser/extensions/permissions_updater.h
+++ b/chrome/browser/extensions/permissions_updater.h
@@ -11,10 +11,6 @@
 #include "base/macros.h"
 #include "extensions/browser/extension_event_histogram_value.h"
 
-namespace base {
-class DictionaryValue;
-}
-
 namespace content {
 class BrowserContext;
 }
@@ -22,7 +18,6 @@ class BrowserContext;
 namespace extensions {
 
 class Extension;
-class ExtensionPrefs;
 class PermissionSet;
 
 // Updates an Extension's active and granted permissions in persistent storage