Add the ability to schedule any pending lossy prefs to be written.

base/prefs/persistent_pref_store.h

Index: base/prefs/persistent_pref_store.h
diff --git a/base/prefs/persistent_pref_store.h b/base/prefs/persistent_pref_store.h
index e70e2a677e1becd441a4aea253a4d00adda35f42..ad8a0a3a66e0ba6afa32e85154e8cb911d030a8f 100644
--- a/base/prefs/persistent_pref_store.h
+++ b/base/prefs/persistent_pref_store.h
@@ -67,6 +67,12 @@ class BASE_PREFS_EXPORT PersistentPrefStore : public WriteablePrefStore {
   // 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 {}
 };