Reland "[FedCM] Split get() into get()+login()"

This reverts commit 2b540bc952136e552b98559fe0ddb4e149b39941.

Reason for revert: Fixed compile error

Original change's description:
> Revert "[FedCM] Split get() into get()+login()"
>
> This reverts commit a6fba024e6fdead47455a413362261326e0ab7a6.
>
> Reason for revert: Might have caused compile failure
> https://ci.chromium.org/p/chromium/builders/ci/linux-archive-rel/62048?
>
> Original change's description:
> > [FedCM] Split get() into get()+login()
> >
> > This is a consequence of
> > fedidcg/FedCM@e49c2bb
> >
> > Bug: 1300009
> > Change-Id: I36839e0e5748d1014e624d64f40d393fec4d2b91
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3499423
> > Reviewed-by: Yi Gu <yigu@chromium.org>
> > Reviewed-by: Sam Goto <goto@chromium.org>
> > Commit-Queue: Christian Biesinger <cbiesinger@chromium.org>
> > Cr-Commit-Position: refs/heads/main@{#977460}
>
> Bug: 1300009
> Change-Id: I6a1e3250f82f4111eac6c841127d044d197af97f
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3499935
> Auto-Submit: Keishi Hattori <keishi@chromium.org>
> Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
> Reviewed-by: Takashi Sakamoto <tasak@google.com>
> Commit-Queue: Keishi Hattori <keishi@chromium.org>
> Owners-Override: Keishi Hattori <keishi@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#977469}

Bug: 1300009
Change-Id: Ibac6509a4a0657b8d2b8c6ff0c32dd1e25fcaf9c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3498694
Reviewed-by: Yi Gu <yigu@chromium.org>
Commit-Queue: Yi Gu <yigu@chromium.org>
Cr-Commit-Position: refs/heads/main@{#977759}

credential-management/fedcm-network-requests.sub.https.html

@@ -21,10 +21,10 @@
       providers: [{
         url: url_prefix,
         clientId: '1',
-        nonce: '1',
       }]
     }
   });
-  assert_equals(result, 'token');
+  const token = await result.login({nonce: '1'});
+  assert_equals(token.idToken, 'token');
 }, 'Test that COEP policy do not apply to FedCM requests');
 </script>

credential-management/fedcm.https.html

@@ -11,29 +11,36 @@
       providers: [{
         url: 'https://idp.test',
         clientId: '1',
-        nonce: '2',
       }]
     }
   };
+  const login_options = {
+    nonce: '2',
+  };
+
 
   fedcm_test(async (t, mock) => {
     mock.returnIdToken("a_token");
-    const token = await navigator.credentials.get(test_options);
-    assert_equals(token, "a_token");
+    const cred = await navigator.credentials.get(test_options);
+    const token = await cred.login(login_options);
+    assert_equals(token.idToken, "a_token");
   }, "Successfully obtaining id_token should resolve the promise.");
 
   fedcm_test(async (t, mock) => {
     mock.returnError("ApprovalDeclined");
-    const result = navigator.credentials.get(test_options);
-    return promise_rejects_dom(t, 'AbortError', result);
+    const cred = await navigator.credentials.get(test_options);
+    const token = cred.login(login_options);
+    return promise_rejects_dom(t, 'AbortError', token);
   }, "User approval decline should reject the promise.");
 
   fedcm_test(async (t, mock) => {
     mock.returnError("ErrorTooManyRequests");
     const first = await navigator.credentials.get(test_options);
+    const first_token = await first.login(login_options);
     const second = await navigator.credentials.get(test_options);
-    assert_equals(first, undefined);
-    return promise_rejects_dom(t, 'AbortError', second);
+    const second_token = await second.login(login_options);
+    assert_equals(first_token.idToken, undefined);
+    return promise_rejects_dom(t, 'AbortError', second_token);
   },
   "When there's a pending request, a second `get` call should be rejected. ",
   "Only one navigator.credentials.get request may be outstanding at one time.");
@@ -90,30 +97,34 @@
 
   fedcm_test(async (t, mock) => {
     mock.returnIdToken("a_token");
-    const token = await navigator.credentials.get({
+    const cred = await navigator.credentials.get({
     federated: {
       providers: [{
         url: 'https://idp.test',
         clientId: '1',
       }]
     }
     });
+    const token = await cred.login(login_options);
 
-    assert_equals(token, "a_token");
+    assert_equals(token.idToken, "a_token");
   }, "nonce is not required in FederatedIdentityProvider.");
 
   fedcm_test(async (t, mock) => {
     let controller = new AbortController();
     mock.returnPendingPromise();
     let aborted = false;
-    const token_promise = navigator.credentials.get({
+    const cred = await navigator.credentials.get({
     federated: {
       providers: [{
         url: 'https://idp.test',
         clientId: '1',
       }],
     },
-    signal: controller.signal,
+    });
+    const token_promise = cred.login({
+      nonce: '2',
+      signal: controller.signal,
     });
     assert_equals(aborted, false);
     controller.abort();
@@ -130,14 +141,17 @@
     let controller = new AbortController();
     mock.returnPendingPromise();
     let aborted = false;
-    const token_promise = navigator.credentials.get({
+    const cred = await navigator.credentials.get({
     federated: {
       providers: [{
         url: 'https://idp.test',
         clientId: '1',
       }],
     },
-    signal: controller.signal,
+    });
+    const token_promise = cred.login({
+      nonce: '2',
+      signal: controller.signal,
     });
     assert_equals(aborted, false);
     controller.abort();
@@ -150,8 +164,9 @@
     assert_equals(aborted, true);
 
     mock.returnIdToken("a_token");
-    const token = await navigator.credentials.get(test_options);
-    assert_equals(token, "a_token");
+    const cred2 = await navigator.credentials.get(test_options);
+    const token = await cred2.login(login_options);
+    assert_equals(token.idToken, "a_token");
   }, "get after abort should work");
 
   promise_test(async t => {