Add a mojo bridge for PersistentPrefStore.

chrome/browser/prefs/profile_pref_store_manager.h

Index: chrome/browser/prefs/profile_pref_store_manager.h
diff --git a/chrome/browser/prefs/profile_pref_store_manager.h b/chrome/browser/prefs/profile_pref_store_manager.h
index e1d0898a000800198770c1a4e40ec96486e433de..0fd82001ca790f41ebbd9eebd1563fd1cd745b9e 100644
--- a/chrome/browser/prefs/profile_pref_store_manager.h
+++ b/chrome/browser/prefs/profile_pref_store_manager.h
@@ -25,6 +25,7 @@ class TrackedPreferenceValidationDelegate;
 namespace base {
 class DictionaryValue;
 class SequencedTaskRunner;
+class SingleThreadTaskRunner;
 }  // namespace base
 
 namespace user_prefs {
@@ -84,9 +85,10 @@ class ProfilePrefStoreManager {
   // An optional |validation_delegate| will be notified
   // of the status of each tracked preference as they are checked.
   PersistentPrefStore* CreateProfilePrefStore(
+      const scoped_refptr<base::SingleThreadTaskRunner>& pref_task_runner,
       const scoped_refptr<base::SequencedTaskRunner>& io_task_runner,
       const base::Closure& on_reset_on_load,
-      TrackedPreferenceValidationDelegate* validation_delegate);
+      base::WeakPtr<TrackedPreferenceValidationDelegate> validation_delegate);
 
   // Initializes the preferences for the managed profile with the preference
   // values in |master_prefs|. Acts synchronously, including blocking IO.