Integrate registry_hash_store_contents with the rest of tracked prefs.

components/user_prefs/tracked/tracked_atomic_preference.cc

Index: components/user_prefs/tracked/tracked_atomic_preference.cc
diff --git a/components/user_prefs/tracked/tracked_atomic_preference.cc b/components/user_prefs/tracked/tracked_atomic_preference.cc
index fe49826dc45f0016ede4e32b495ddb4cc4584ce3..2415d7f844a909a3ebbdcbd70741b05c8dff52ae 100644
--- a/components/user_prefs/tracked/tracked_atomic_preference.cc
+++ b/components/user_prefs/tracked/tracked_atomic_preference.cc
@@ -24,6 +24,10 @@ TrackedAtomicPreference::TrackedAtomicPreference(
       delegate_(delegate) {
 }
 
+TrackedPreferenceType TrackedAtomicPreference::GetType() const {
+  return TrackedPreferenceType::ATOMIC;
+}
+
 void TrackedAtomicPreference::OnNewValue(
     const base::Value* value,
     PrefHashStoreTransaction* transaction) const {
@@ -32,20 +36,32 @@ void TrackedAtomicPreference::OnNewValue(
 
 bool TrackedAtomicPreference::EnforceAndReport(
     base::DictionaryValue* pref_store_contents,
-    PrefHashStoreTransaction* transaction) const {
+    PrefHashStoreTransaction* transaction,
+    PrefHashStoreTransaction* external_validation_transaction) const {
   const base::Value* value = NULL;
   pref_store_contents->Get(pref_path_, &value);
   PrefHashStoreTransaction::ValueState value_state =
       transaction->CheckValue(pref_path_, value);
-
   helper_.ReportValidationResult(value_state, transaction->GetStoreUMASuffix());
 
-  TrackedPreferenceHelper::ResetAction reset_action =
-      helper_.GetAction(value_state);
+  PrefHashStoreTransaction::ValueState external_validation_value_state =
+      PrefHashStoreTransaction::UNCHANGED;
+  if (external_validation_transaction) {
+    external_validation_value_state =
+        external_validation_transaction->CheckValue(pref_path_, value);
+    helper_.ReportValidationResult(
+        external_validation_value_state,
+        external_validation_transaction->GetStoreUMASuffix());
+
+    // TODO(proberge): Call delegate_->OnAtomicPreferenceValidation.
+  }
+
   if (delegate_) {
     delegate_->OnAtomicPreferenceValidation(pref_path_, value, value_state,
                                             helper_.IsPersonal());
   }
+  TrackedPreferenceHelper::ResetAction reset_action =
+      helper_.GetAction(value_state);
   helper_.ReportAction(reset_action);
 
   bool was_reset = false;
@@ -61,5 +77,16 @@ bool TrackedAtomicPreference::EnforceAndReport(
     transaction->StoreHash(pref_path_, new_value);
   }
 
+  // Update MACs in the external store if there is one and there either was a
+  // reset or external validation failed.
+  if (external_validation_transaction &&
+      (was_reset ||
+       external_validation_value_state !=
+           PrefHashStoreTransaction::UNCHANGED)) {
+    const base::Value* new_value = nullptr;
+    pref_store_contents->Get(pref_path_, &new_value);
+    external_validation_transaction->StoreHash(pref_path_, new_value);
+  }
+
   return was_reset;
 }