Add ManagedUserTokenFetcher to fetch scoped-down tokens.

chrome/browser/signin/oauth2_token_service.h

Index: chrome/browser/signin/oauth2_token_service.h
diff --git a/chrome/browser/signin/oauth2_token_service.h b/chrome/browser/signin/oauth2_token_service.h
index 9260f4179fae0ee9cdcb7d250ff90b577a074417..777ee28390dbbb90c411f81c1b98e6dbde27e1d0 100644
--- a/chrome/browser/signin/oauth2_token_service.h
+++ b/chrome/browser/signin/oauth2_token_service.h
@@ -81,9 +81,11 @@ class OAuth2TokenService {
   // Checks in the cache for a valid access token, and if not found starts
   // a request for an OAuth2 access token using the OAuth2 refresh token
   // maintained by this instance. The caller owns the returned Request.
-  // |scopes| is the set of scopes to get an access token for, |consumer| is
-  // the object that will be called back with results if the returned request
-  // is not deleted.
+  // |scopes| is the set of scopes to get an access token for. If the set is
+  // empty, the returned access token will have the same scope as the refresh
+  // token.
+  // |consumer| is the object that will be called back with results if the
+  // returned request is not deleted.
   virtual scoped_ptr<Request> StartRequest(const ScopeSet& scopes,
                                            Consumer* consumer);
 
@@ -148,12 +150,6 @@ class OAuth2TokenService {
     Consumer* const consumer_;
   };
 
-  // Informs the consumer of |request| fetch results.
-  static void InformConsumer(base::WeakPtr<RequestImpl> request,
-                             const GoogleServiceAuthError& error,
-                             const std::string& access_token,
-                             const base::Time& expiration_date);
-
  private:
   // Class that fetches an OAuth2 access token for a given set of scopes and
   // OAuth2 refresh token.