Update from https://crrev.com/333737

base/prefs/persistent_pref_store.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_PREFS_PERSISTENT_PREF_STORE_H_
 #define BASE_PREFS_PERSISTENT_PREF_STORE_H_
 
 #include <string>
 
 #include "base/prefs/base_prefs_export.h"
@@ skipping 49 matching lines @@
 
   // Reads the preferences from disk asynchronously. Notifies observers via
   // "PrefStore::OnInitializationCompleted" when done. Also it fires
   // |error_delegate| if it is not NULL and reading error has occurred.
   // Owns |error_delegate|.
   virtual void ReadPrefsAsync(ReadErrorDelegate* error_delegate) = 0;
 
   // Lands any pending writes to disk.
   virtual void CommitPendingWrite() = 0;
 
+  // Schedule a write if there is any lossy data pending. Unlike
+  // CommitPendingWrite() this does not immediately sync to disk, instead it
+  // triggers an eventual write if there is lossy data pending and if there
+  // isn't one scheduled already.
+  virtual void SchedulePendingLossyWrites() = 0;
+
  protected:
   ~PersistentPrefStore() override {}
 };
 
 #endif  // BASE_PREFS_PERSISTENT_PREF_STORE_H_