Add clean up logic to navigator.credentials layout tests

third_party/WebKit/LayoutTests/http/tests/credentialmanager/credentialscontainer-get-errors.html

Index: third_party/WebKit/LayoutTests/http/tests/credentialmanager/credentialscontainer-get-errors.html
diff --git a/third_party/WebKit/LayoutTests/http/tests/credentialmanager/credentialscontainer-get-errors.html b/third_party/WebKit/LayoutTests/http/tests/credentialmanager/credentialscontainer-get-errors.html
index 043ae352d61d0798d050486f24e0cb4ca0edb209..347fc413fa6d90d72063b970e1a654354afa5276 100644
--- a/third_party/WebKit/LayoutTests/http/tests/credentialmanager/credentialscontainer-get-errors.html
+++ b/third_party/WebKit/LayoutTests/http/tests/credentialmanager/credentialscontainer-get-errors.html
@@ -3,29 +3,26 @@
 <script src="../resources/testharnessreport.js"></script>
 <script src="/serviceworker/resources/interfaces.js"></script>
 <script>
-function stubResolverUndefinedChecker(c) {
-    assert_equals(c, undefined);
-    this.done();
-}
-
-function stubRejectionChecker(reason) {
-    assert_unreached("get() should not reject, but did: " + reason.name);
-}
+add_completion_callback(() => {
+    if (window.testRunner) {
+        // Clear the error value by passing an empty string.
+        testRunner.setMockCredentialManagerError("");
+    }
+});
 
 promise_test(function (t) {
     if (window.testRunner)
-        testRunner.addMockCredentialManagerError("pending");
+        testRunner.setMockCredentialManagerError("pending");
     return promise_rejects(t, "InvalidStateError", navigator.credentials.get({ password: true }));
 });
 promise_test(function (t) {
     if (window.testRunner)
-        testRunner.addMockCredentialManagerError("disabled");
+        testRunner.setMockCredentialManagerError("disabled");
     return promise_rejects(t, "InvalidStateError", navigator.credentials.get({ password: true }));
 });
 promise_test(function (t) {
     if (window.testRunner)
-        testRunner.addMockCredentialManagerError("unknown");
+        testRunner.setMockCredentialManagerError("unknown");
     return promise_rejects(t, "NotReadableError", navigator.credentials.get({ password: true }));
 });
 </script>
-