We should use UserID object to identify users instead of username.

chrome/browser/drive/drive_api_service.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/drive/drive_api_service.h"
 
 #include <string>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/strings/stringprintf.h"
 #include "chrome/browser/drive/drive_api_util.h"
+#include "components/user_manager/user_id.h"
 #include "google_apis/drive/auth_service.h"
 #include "google_apis/drive/drive_api_parser.h"
 #include "google_apis/drive/drive_api_requests.h"
 #include "google_apis/drive/request_sender.h"
 #include "google_apis/google_api_keys.h"
 #include "net/url_request/url_request_context_getter.h"
 
 using google_apis::AboutResourceCallback;
 using google_apis::AppList;
 using google_apis::AppListCallback;
@@ skipping 760 matching lines @@
 
   google_apis::drive::AppsDeleteRequest* request =
       new google_apis::drive::AppsDeleteRequest(sender_.get(), url_generator_,
                                                 callback);
   request->set_app_id(app_id);
   return sender_->StartRequestWithRetry(request);
 }
 
 google_apis::CancelCallback DriveAPIService::AddPermission(
     const std::string& resource_id,
-    const std::string& email,
+    const user_manager::UserID& user_id,
     google_apis::drive::PermissionRole role,
     const google_apis::EntryActionCallback& callback) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(!callback.is_null());
 
   google_apis::drive::PermissionsInsertRequest* request =
       new google_apis::drive::PermissionsInsertRequest(sender_.get(),
                                                        url_generator_,
                                                        callback);
   request->set_id(resource_id);
   request->set_role(role);
   request->set_type(google_apis::drive::PERMISSION_TYPE_USER);
-  request->set_value(email);
+  request->set_value(user_id.GetUserEmail());
   return sender_->StartRequestWithRetry(request);
 }
 
 bool DriveAPIService::HasAccessToken() const {
   DCHECK(thread_checker_.CalledOnValidThread());
   return sender_->auth_service()->HasAccessToken();
 }
 
 void DriveAPIService::RequestAccessToken(const AuthStatusCallback& callback) {
   DCHECK(thread_checker_.CalledOnValidThread());
@@ skipping 47 matching lines @@
   // RequestSender before the request is committed because the request has a
   // reference to RequestSender and we should ensure to delete the request when
   // the sender is deleted. Resolve the circulating dependency and fix it.
   const google_apis::CancelCallback callback =
       sender_->StartRequestWithRetry(request.release());
   return make_scoped_ptr<BatchRequestConfiguratorInterface>(
       new BatchRequestConfigurator(weak_ref, callback));
 }
 
 }  // namespace drive