Remove the #enable-fast-user-switcher flag.

components/signin/core/common/signin_switches.cc

 // Copyright 2014 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 "components/signin/core/common/signin_switches.h"
 
 namespace switches {
 
 // Clears the token service before using it. This allows simulating the
 // expiration of credentials during testing.
@@ skipping 24 matching lines @@
 // Enables new profile management system, including lock mode.
 const char kEnableNewProfileManagement[] = "new-profile-management";
 
 // Enable sending EnableRefreshTokenAnnotationRequest.
 extern const char kEnableRefreshTokenAnnotationRequest[] =
     "enable-refresh-token-annotation-request";
 
 // Enables multiple account versions of chrome.identity APIs.
 const char kExtensionsMultiAccount[] = "extensions-multi-account";
 
-// Allows displaying the list of existing profiles in the avatar bubble for
-// fast switching between profiles.
-const char kFastUserSwitching[] = "fast-user-switching";
-
 // Enables using GAIA information to populate profile name and icon.
 const char kGoogleProfileInfo[] = "google-profile-info";
 
 }  // namespace switches