[Password Manager] Remove the "manager-for-sync-signin" flags.

components/password_manager/core/common/password_manager_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/password_manager/core/common/password_manager_switches.h"
 
 namespace password_manager {
 
 namespace switches {
 
 // Force the password manager to allow sync credentials to be autofilled.
 const char kAllowAutofillSyncCredential[] = "allow-autofill-sync-credential";
 
 // Disable affiliation based matching, so that credentials stored for an Android
 // application will not be considered matches for, and will not be filled into
 // corresponding Web applications.
 const char kDisableAffiliationBasedMatching[] =
     "disable-affiliation-based-matching";
 
 // Disable dropping the credential used to sync passwords.
 const char kDisableDropSyncCredential[] = "disable-drop-sync-credential";
 
-// Disable both saving and filling for the sync signin form.
-const char kDisableManagerForSyncSignin[] = "disable-manager-for-sync-signin";
-
 // Disallow autofilling of the sync credential.
 const char kDisallowAutofillSyncCredential[] =
     "disallow-autofill-sync-credential";
 
 // Disallow autofilling of the sync credential only for transactional reauth
 // pages.
 const char kDisallowAutofillSyncCredentialForReauth[] =
     "disallow-autofill-sync-credential-for-reauth";
 
 // Enable affiliation based matching, so that credentials stored for an Android
 // application will also be considered matches for, and be filled into
 // corresponding Web applications.
 const char kEnableAffiliationBasedMatching[] =
     "enable-affiliation-based-matching";
 
 // Enable dropping the credential used to sync passwords.
 const char kEnableDropSyncCredential[] = "enable-drop-sync-credential";
 
-// Enable saving and filling for the sync signin form. Currently the default
-// behavior.
-const char kEnableManagerForSyncSignin[] = "enable-manager-for-sync-signin";
-
 }  // namespace switches
 
 }  // namespace password_manager