Deprecate CredentialRequestOptions.unmediated in favor mediation enum

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

Index: third_party/WebKit/LayoutTests/http/tests/credentialmanager/credentialscontainer-get-basics.html
diff --git a/third_party/WebKit/LayoutTests/http/tests/credentialmanager/credentialscontainer-get-basics.html b/third_party/WebKit/LayoutTests/http/tests/credentialmanager/credentialscontainer-get-basics.html
index a4531acd1c997aef56405d5d123eb48a2a2f0e08..b6dedacd41df4479ab2cb02f4c9c8463b664cebb 100644
--- a/third_party/WebKit/LayoutTests/http/tests/credentialmanager/credentialscontainer-get-basics.html
+++ b/third_party/WebKit/LayoutTests/http/tests/credentialmanager/credentialscontainer-get-basics.html
@@ -102,6 +102,17 @@ add_completion_callback(() => {
 }());
 
 (function() {
+    var t = async_test("navigator.credentials.get() with a valid options including mediation.");
+    t.step(function () {
+        navigator.credentials.get({
+            mediation: "silent"
+        }).then(
+            t.step_func(stubResolverUndefinedChecker.bind(t)),
+            t.step_func(stubRejectionChecker.bind(t)));
+    });
+}());
+
+(function() {
     var t = async_test("navigator.credentials.get() with an options including an unknown attribute.");
     t.step(function () {
         navigator.credentials.get({