Query libsecret password after matching attributes against login form

Call secret_item_load_secret_sync only after matching the attributes of the
secret item against the requested login form. This does not only improve the
security as we don't query all available passwords, but also reduces the number
of required dbus calls. The current code, for example, queried all passwords,
even if none of the entries matched.

R=dvadym@chromium.org

Bug: 859305
Change-Id: I5e0432942d71d86fc9b06b86318b123614ab1be1
Reviewed-on: https://chromium-review.googlesource.com/1137816Reviewed-by: Vadym Doroshenko <dvadym@chromium.org>
Commit-Queue: Vadym Doroshenko <dvadym@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575218}

chrome/browser/password_manager/native_backend_libsecret.cc

@@ -491,13 +491,6 @@ NativeBackendLibsecret::ConvertFormList(
   for (GList* element = g_list_first(found); element != nullptr;
        element = g_list_next(element)) {
     SecretItem* secretItem = static_cast<SecretItem*>(element->data);
-    LibsecretLoader::secret_item_load_secret_sync(secretItem, nullptr, &error);
-    if (error) {
-      LOG(ERROR) << "Unable to load secret item" << error->message;
-      g_error_free(error);
-      error = nullptr;
-      continue;
-    }
     GHashTable* attrs = LibsecretLoader::secret_item_get_attributes(secretItem);
     std::unique_ptr<PasswordForm> form(FormOutOfAttributes(attrs));
     g_hash_table_unref(attrs);
@@ -526,6 +519,14 @@ NativeBackendLibsecret::ConvertFormList(
       }
     }
 
+    LibsecretLoader::secret_item_load_secret_sync(secretItem, nullptr, &error);
+    if (error) {
+      LOG(ERROR) << "Unable to load secret item" << error->message;
+      g_error_free(error);
+      error = nullptr;
+      continue;
+    }
+
     SecretValue* secretValue =
         LibsecretLoader::secret_item_get_secret(secretItem);
     if (secretValue) {