Let chrome_prefs handle Preferences initialization from master_preferences.

chrome/browser/prefs/chrome_pref_service_factory.h

Index: chrome/browser/prefs/chrome_pref_service_factory.h
diff --git a/chrome/browser/prefs/chrome_pref_service_factory.h b/chrome/browser/prefs/chrome_pref_service_factory.h
index c8a119d09a9225429307d10d7421379b38ad362c..2366b4f8d0ae196d6cf02d3410d6d8e41ed24a51 100644
--- a/chrome/browser/prefs/chrome_pref_service_factory.h
+++ b/chrome/browser/prefs/chrome_pref_service_factory.h
@@ -9,6 +9,7 @@
 #include "base/memory/scoped_ptr.h"
 
 namespace base {
+class DictionaryValue;
 class FilePath;
 class SequencedTaskRunner;
 }
@@ -62,13 +63,19 @@ scoped_ptr<PrefServiceSyncable> CreateProfilePrefs(
     const scoped_refptr<user_prefs::PrefRegistrySyncable>& pref_registry,
     bool async);
 
-// Initializes a preference hash store for the profile preferences file at
+// Initializes the |pref_hash_store| for the profile preferences file at
 // |pref_filename| without actually loading the profile.
-void InitializeHashStoreForPrefFile(
+void InitializeHashStoreFromPrefFile(
     const base::FilePath& pref_filename,
     base::SequencedTaskRunner* pref_io_task_runner,
     scoped_ptr<PrefHashStore> pref_hash_store);
 
+// Initializes the |pref_hash_store| via the preference values present in
+// |master_prefs|.
+void InitializeHashStoreFromMasterPrefs(
+    const base::DictionaryValue& master_prefs,
+    scoped_ptr<PrefHashStore> pref_hash_store);
+
 }  // namespace chrome_prefs
 
 #endif  // CHROME_BROWSER_PREFS_CHROME_PREF_SERVICE_FACTORY_H_