Integrate registry_hash_store_contents with the rest of tracked prefs.

components/user_prefs/tracked/pref_hash_store.h

Index: components/user_prefs/tracked/pref_hash_store.h
diff --git a/components/user_prefs/tracked/pref_hash_store.h b/components/user_prefs/tracked/pref_hash_store.h
index 2fdc617301ae1fea64526ae16fe5d6621c272406..096895268ef51796773c8b959cedb4dc1ac96fa8 100644
--- a/components/user_prefs/tracked/pref_hash_store.h
+++ b/components/user_prefs/tracked/pref_hash_store.h
@@ -10,6 +10,11 @@
 class HashStoreContents;
 class PrefHashStoreTransaction;
 
+namespace base {
+class DictionaryValue;
+class Value;
+}  // namespace base
+
 // Holds the configuration and implementation used to calculate and verify
 // preference MACs.
 // TODO(gab): Rename this class as it is no longer a store.
@@ -21,8 +26,25 @@ class PrefHashStore {
   // of operations on the hash store. |storage| MAY be used as the backing store
   // depending on the implementation. Therefore the HashStoreContents used for
   // related transactions should correspond to the same underlying data store.
+  // Does not own the HashStoreContents; callers must ensure transaction must
+  // not outlive |storage|.
   virtual std::unique_ptr<PrefHashStoreTransaction> BeginTransaction(
-      std::unique_ptr<HashStoreContents> storage) = 0;
+      HashStoreContents* storage) = 0;
+
+  // Computes the MAC to be associated with |path| and |value| in this store.
+  // PrefHashStoreTransaction typically uses this internally but it's also
+  // exposed for users that want to compute MACs ahead of time for asynchronous
+  // operations.
+  virtual std::string ComputeMac(const std::string& path,
+                                 const base::Value* value) = 0;
+
+  // Computes the MAC to be associated with |path| and |split_values| in this
+  // store. PrefHashStoreTransaction typically uses this internally but it's
+  // also exposed for users that want to compute MACs ahead of time for
+  // asynchronous operations.
+  virtual std::unique_ptr<base::DictionaryValue> ComputeSplitMacs(
+      const std::string& path,
+      const base::DictionaryValue* split_values) = 0;
 };
 
 #endif  // COMPONENTS_PREFS_TRACKED_PREF_HASH_STORE_H_