Specify account labels

Bug: #553

spec/index.bs

@@ -860,6 +860,12 @@ the exception thrown.
                 {{IdentityProviderAccount/domain_hints}} does not [=list/contain=] |provider|'s
                 {{IdentityProviderRequestOptions/domainHint}}.
         1. If |accountList| is now empty, go to the [=mismatch dialog step=].
+    1. If |config|.{{IdentityProviderAPIConfig/accounts}}.{{IdentityProviderLabelConfig/include}}
+        was specified:
+        1. For every |account| in |accountList|, remove |account| from |accountList| if |account|'s
+            {{IdentityProviderAccount/labels}} does not [=list/contain=]
+            |config|.{{IdentityProviderAPIConfig/accounts}}.{{IdentityProviderLabelConfig/include}}.
+        1. If |accountList| is now empty, go to the [=mismatch dialog step=].
     1. For each |acc| in |accountsList|:
         1. If |acc|["{{IdentityProviderAccount/picture}}"] is present, [=fetch the account picture=]
             with |acc| and |globalObject|.
@@ -1053,13 +1059,18 @@ dictionary IdentityProviderBranding {
   USVString name;
 };
 
+dictionary IdentityProviderLabelConfig {
+  USVString include;
+};
+
 dictionary IdentityProviderAPIConfig {
   required USVString accounts_endpoint;
   required USVString client_metadata_endpoint;
   required USVString id_assertion_endpoint;
   required USVString login_url;
   USVString disconnect_endpoint;
   IdentityProviderBranding branding;
+  IdentityProviderLabelConfig accounts;
 };
 </xmp>
 
@@ -1138,6 +1149,7 @@ dictionary IdentityProviderAccount {
   sequence<USVString> approved_clients;
   sequence<DOMString> login_hints;
   sequence<DOMString> domain_hints;
+  sequence<DOMString> labels;
 };
 dictionary IdentityProviderAccountList {
   sequence<IdentityProviderAccount> accounts;
@@ -1813,6 +1825,9 @@ Every {{IdentityProviderAccount}} is expected to have members with the following
     ::  A list of strings which correspond to all of the domain hints which match with this account.
         An [=RP=] can use the {{IdentityProviderRequestOptions/domainHint}} to request that only an account
         matching a given value or containing some domain hint is shown to the user.
+    :   <dfn>labels</dfn>
+    ::  A list of strings which give the accounts a list of labels. The config file can specify a filter
+        for a label string.
 </dl>
 
 For example:
@@ -1828,7 +1843,7 @@ For example:
    "picture": "https://idp.example/profile/123",
    "approved_clients": ["123", "456", "789"],
    "login_hints": ["john_doe"],
-   "domain_hints": ["idp.example"],
+   "domain_hints": ["idp.example"]
   }, {
    "id": "5678",
    "given_name": "Johnny",
@@ -1838,6 +1853,7 @@ For example:
    "approved_clients": ["abc", "def", "ghi"],
    "login_hints": ["[email protected]", "id=5678"],
    "domain_hints": ["idp.example"],
+   "labels:" ["l1"]
   }]
 }
 ```