Allow normal users to change per session flags.

chrome/browser/ui/webui/flags_ui.h

Index: chrome/browser/ui/webui/flags_ui.h
diff --git a/chrome/browser/ui/webui/flags_ui.h b/chrome/browser/ui/webui/flags_ui.h
index 0cac343829d09634ce8296c13989aced7401cc26..98fb3ddbd3b91a2b9ab496351e0e0080d56ec1b7 100644
--- a/chrome/browser/ui/webui/flags_ui.h
+++ b/chrome/browser/ui/webui/flags_ui.h
@@ -9,6 +9,7 @@
 #include "ui/base/layout.h"
 
 class PrefRegistrySimple;
+class PrefRegistrySyncable;
 
 namespace base {
 class RefCountedMemory;
@@ -21,6 +22,7 @@ class FlagsUI : public content::WebUIController {
   static base::RefCountedMemory* GetFaviconResourceBytes(
       ui::ScaleFactor scale_factor);
   static void RegisterPrefs(PrefRegistrySimple* registry);
+  static void RegisterUserPrefs(PrefRegistrySyncable* registry);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlagsUI);