[FedCM] Remove redundant early return in OnTokenResponseReceived()

This CL removes the early return in OnTokenResponseReceived(). It is
redundant because FederatedAuthRequestImpl::CleanUp() invalidates all
weak ptrs.

BUG=None

Change-Id: Ic49c9067cbc411ddc6eed605109b81dc4c80b205
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4116751
Reviewed-by: Yi Gu <yigu@chromium.org>
Commit-Queue: Peter Kotwicz <pkotwicz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1085275}
diff --git a/content/browser/webid/federated_auth_request_impl.cc b/content/browser/webid/federated_auth_request_impl.cc
index e8ad035..65d1f73 100644
--- a/content/browser/webid/federated_auth_request_impl.cc
+++ b/content/browser/webid/federated_auth_request_impl.cc
@@ -1078,9 +1078,6 @@
     const IdentityProviderConfig& idp,
     IdpNetworkRequestManager::FetchStatus status,
     const std::string& id_token) {
-  if (!auth_request_callback_)
-    return;
-
   // When fetching id tokens we show a "Verify" sheet to users in case fetching
   // takes a long time due to latency etc.. In case that the fetching process is
   // fast, we still want to show the "Verify" sheet for at least