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

chrome/browser/drive/drive_api_service.cc

Index: chrome/browser/drive/drive_api_service.cc
diff --git a/chrome/browser/drive/drive_api_service.cc b/chrome/browser/drive/drive_api_service.cc
index b42f4c0d4f9c4caeb7c8783263826e65aa23d1a7..53d412e6d2cb1eee82ced3cd3e6ecf053dcd41e3 100644
--- a/chrome/browser/drive/drive_api_service.cc
+++ b/chrome/browser/drive/drive_api_service.cc
@@ -10,6 +10,7 @@
 #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"
@@ -790,7 +791,7 @@ CancelCallback DriveAPIService::UninstallApp(
 
 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());
@@ -803,7 +804,7 @@ google_apis::CancelCallback DriveAPIService::AddPermission(
   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);
 }