Add a dummy entry with libsecret when initializing OSCrypt.

components/os_crypt/key_storage_libsecret_unittest.cc

Index: components/os_crypt/key_storage_libsecret_unittest.cc
diff --git a/components/os_crypt/key_storage_libsecret_unittest.cc b/components/os_crypt/key_storage_libsecret_unittest.cc
index e8e27ee6d65578a9696138e97df358e4cc9fbd9d..aa1953a92a0b2c8dd94f839fbf95f85f515a67de 100644
--- a/components/os_crypt/key_storage_libsecret_unittest.cc
+++ b/components/os_crypt/key_storage_libsecret_unittest.cc
@@ -101,6 +101,10 @@ gboolean MockLibsecretLoader::mock_secret_password_store_sync(
     GCancellable* cancellable,
     GError** error,
     ...) {
+  // TODO(crbug.com/660005) We don't read the dummy we store to unlock keyring.
+  if (strcmp("_chrome_dummy_schema_for_unlocking", schema->name) == 0)
+    return true;
+
   EXPECT_STREQ(kKeystoreSchemaV2.name, schema->name);
   delete stored_password_mock_ptr_;
   stored_password_mock_ptr_ = new MockSecretValue(password);