cros: Add flag to enable pin on sign-in screen.

chrome/browser/flag_descriptions.cc

 // Copyright 2017 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/flag_descriptions.h"
 
 namespace flag_descriptions {
 
 //  Material Design version of chrome://bookmarks
 
@@ skipping 2887 matching lines @@
 
 const char kWakeOnPacketsName[] = "Wake On Packets";
 
 const char kWakeOnPacketsDescription[] =
     "Enables waking the device based on the receipt of some network "
     "packets.";
 
 const char kQuickUnlockPin[] = "Quick Unlock (PIN)";
 
 const char kQuickUnlockPinDescription[] =
-    "Enabling PIN quick unlock allows you to use a PIN to unlock your "
-    "Chromebook on the lock screen after you have signed into your device.";
+    "Enabling PIN quick unlock allows you to use a PIN to unlock your ChromeOS "
+    "device on the lock screen after you have signed into your device.";
+
+const char kQuickUnlockPinSignin[] = "Enable PIN when logging in.";
+
+const char kQuickUnlockPinSigninDescription[] =
+    "Enabling PIN allows you to use a PIN to sign in and unlock your ChromeOS "
+    "device. After changing this flag PIN needs to be set up again.";
 
 const char kQuickUnlockFingerprint[] = "Quick Unlock (Fingerprint)";
 
 const char kQuickUnlockFingerprintDescription[] =
     "Enabling fingerprint quick unlock allows you to setup and use a "
     "fingerprint to unlock your Chromebook on the lock screen after you "
     "have signed into your device.";
 
 const char kExperimentalAccessibilityFeaturesName[] =
     "Experimental accessibility features";
@@ skipping 87 matching lines @@
 const char kEnableCopylessPasteDescription[] =
     "Provide suggestions for text input, based on your recent context. For "
     "example, if you looked at a restaurant website and switched to the Maps "
     "app, the keyboard would offer the name of that restaurant as a suggestion "
     "to enter into the search bar. The data is indexed locally, and never sent "
     "to the server. It's disabled in incognito mode.";
 
 #endif  // defined(OS_ANDROID)
 
 }  // namespace flag_descriptions