Remove enable-iframe-based-signin 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.
 const char kClearTokenService[] = "clear-token-service";
 
 // Disables consistent identity features.
 const char kDisableAccountConsistency[] = "disable-account-consistency";
 
 // Disables new profile management system, including new profile chooser UI.
 const char kDisableNewProfileManagement[] = "disable-new-profile-management";
 
 // Disables new gaia password-separated sign in flow.
 const char kDisablePasswordSeparatedSigninFlow[] =
     "disable-password-separated-signin-flow";
 
 // Disables sending signin scoped device id to LSO with refresh token request.
 const char kDisableSigninScopedDeviceId[] = "disable-signin-scoped-device-id";
 
 // Enables consistent identity features.
 const char kEnableAccountConsistency[] = "enable-account-consistency";
 
-// Enables the old iframe-based flow for sign in.  When not enabled, uses the
-// webview-based flow.
-const char kEnableIframeBasedSignin[] = "enable-iframe-based-signin";
-
 // Enables new gaia password-separated sign in flow.
 const char kEnablePasswordSeparatedSigninFlow[] =
     "enable-password-separated-signin-flow";
 
 // Enables new profile management system, including lock mode.
 const char kEnableNewProfileManagement[] = "new-profile-management";
 
 // Enables 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";
 
 // Enables using GAIA information to populate profile name and icon.
 const char kGoogleProfileInfo[] = "google-profile-info";
 
 }  // namespace switches