[DICE] Enable sync for an account that is already present in the token service.

chrome/browser/policy/cloud/user_policy_signin_service.h

Index: chrome/browser/policy/cloud/user_policy_signin_service.h
diff --git a/chrome/browser/policy/cloud/user_policy_signin_service.h b/chrome/browser/policy/cloud/user_policy_signin_service.h
index 65d94865b287a8b6a2ec53be92d87dfadd4bfcbb..7cd0009826a0be9227f587c8af6d5e3458e9b713 100644
--- a/chrome/browser/policy/cloud/user_policy_signin_service.h
+++ b/chrome/browser/policy/cloud/user_policy_signin_service.h
@@ -47,9 +47,18 @@ class UserPolicySigninService : public UserPolicySigninServiceBase,
   // the user is not signed in yet (ProfileOAuth2TokenService does not have
   // any tokens yet to prevent services from using it until after we've fetched
   // policy).
-  void RegisterForPolicy(const std::string& username,
-                         const std::string& oauth2_login_token,
-                         const PolicyRegistrationCallback& callback);
+  void RegisterForPolicyWithLoginToken(
+      const std::string& username,
+      const std::string& oauth2_login_token,
+      const PolicyRegistrationCallback& callback);
+
+  // Registers a CloudPolicyClient for fetching policy for a user. |username| is
+  // explicitly passed because the user is not yet authenticated, but the token
+  // service has a refresh token available for |account_id|.
+  void RegisterForPolicyWithAccountId(
+      const std::string& username,
+      const std::string& account_id,
+      const PolicyRegistrationCallback& callback);
 
   // OAuth2TokenService::Observer implementation:
   void OnRefreshTokenAvailable(const std::string& account_id) override;