[signin][Mice] Do not call FireRefreshTokensLoaded too early

This was causing a crash on startup if an account was removed from the
device while Chrome was not running.

Bug: 936953
Change-Id: I45662ace9c498b6db8b719251e8f7f461dc5531f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1505447Reviewed-by: Boris Sazonov <bsazonov@chromium.org>
Commit-Queue: David Roger <droger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638656}

components/signin/core/browser/oauth2_token_service_delegate_android.cc

@@ -485,7 +485,8 @@ void OAuth2TokenServiceDelegateAndroid::LoadCredentials(
     const std::string& primary_account_id) {
   DCHECK_EQ(LOAD_CREDENTIALS_NOT_STARTED, load_credentials_state());
   set_load_credentials_state(LOAD_CREDENTIALS_IN_PROGRESS);
-  if (primary_account_id.empty()) {
+  if (primary_account_id.empty() &&
+      !base::FeatureList::IsEnabled(signin::kMiceFeature)) {
     FireRefreshTokensLoaded();
     return;
   }