components: Move PrefRegistrySyncable into user_prefs namespace.

chrome/browser/content_settings/content_settings_default_provider.h

Index: chrome/browser/content_settings/content_settings_default_provider.h
diff --git a/chrome/browser/content_settings/content_settings_default_provider.h b/chrome/browser/content_settings/content_settings_default_provider.h
index 9bc124ba49e467afea445eb8f82725ce8ad443fe..92c2e3ef5075b07dc5c7566ced75714efa406b44 100644
--- a/chrome/browser/content_settings/content_settings_default_provider.h
+++ b/chrome/browser/content_settings/content_settings_default_provider.h
@@ -15,9 +15,12 @@
 #include "base/synchronization/lock.h"
 #include "chrome/browser/content_settings/content_settings_observable_provider.h"
 
-class PrefRegistrySyncable;
 class PrefService;
 
+namespace user_prefs {
+class PrefRegistrySyncable;
+}
+
 namespace content_settings {
 
 // Provider that provides default content settings based on
@@ -25,7 +28,7 @@ namespace content_settings {
 // default values.
 class DefaultProvider : public ObservableProvider {
  public:
-  static void RegisterUserPrefs(PrefRegistrySyncable* registry);
+  static void RegisterUserPrefs(user_prefs::PrefRegistrySyncable* registry);
 
   DefaultProvider(PrefService* prefs,
                   bool incognito);