Introduce PrefRegistrySyncable, simplifying PrefServiceSyncable.

chrome/browser/content_settings/content_settings_default_provider.cc

Index: chrome/browser/content_settings/content_settings_default_provider.cc
diff --git a/chrome/browser/content_settings/content_settings_default_provider.cc b/chrome/browser/content_settings/content_settings_default_provider.cc
index 9a9c738aa6180c1862c9dc5675f4315989330eb5..56519555f5244658959d138d8d515ff2a8116a9c 100644
--- a/chrome/browser/content_settings/content_settings_default_provider.cc
+++ b/chrome/browser/content_settings/content_settings_default_provider.cc
@@ -13,6 +13,7 @@
 #include "base/metrics/histogram.h"
 #include "chrome/browser/content_settings/content_settings_rule.h"
 #include "chrome/browser/content_settings/content_settings_utils.h"
+#include "chrome/browser/prefs/pref_registry_syncable.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/prefs/scoped_user_pref_update.h"
 #include "chrome/common/chrome_notification_types.h"
@@ -87,7 +88,7 @@ class DefaultRuleIterator : public RuleIterator {
 }  // namespace
 
 // static
-void DefaultProvider::RegisterUserPrefs(PrefServiceSyncable* prefs) {
+void DefaultProvider::RegisterUserPrefs(PrefRegistrySyncable* registry) {
   // The registration of the preference prefs::kDefaultContentSettings should
   // also include the default values for default content settings. This allows
   // functional tests to get default content settings by reading the preference
@@ -95,9 +96,9 @@ void DefaultProvider::RegisterUserPrefs(PrefServiceSyncable* prefs) {
   // TODO(markusheintz): Write pyauto hooks for the content settings map as
   // content settings should be read from the host content settings map.
   DictionaryValue* default_content_settings = new DictionaryValue();
-  prefs->RegisterDictionaryPref(prefs::kDefaultContentSettings,
-                                default_content_settings,
-                                PrefServiceSyncable::SYNCABLE_PREF);
+  registry->RegisterDictionaryPref(prefs::kDefaultContentSettings,
+                                   default_content_settings,
+                                   PrefRegistrySyncable::SYNCABLE_PREF);
 }
 
 DefaultProvider::DefaultProvider(PrefService* prefs, bool incognito)