Adding about:flags option to enable guest mode.

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index 76ebb88435c774b37562b495c73276f3f8ab89cf..77cdfda594c5cd2bc1a28c1da2c564f0337be511 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -15253,6 +15253,13 @@ Some features may be unavailable.  Please check that the profile exists and you
       The web-based flow permits using verification codes instead of ASPs during authentication.
     </message>
 
+    <message name="IDS_FLAGS_DESKTOP_GUEST_MODE_NAME" desc="Name of about:flags option to turn on desktop guest mode">
+      Enable desktop guest mode
+    </message>
+    <message name="IDS_FLAGS_DESKTOP_GUEST_MODE_DESCRIPTION" desc="Description of about:flags option to turn on desktop guest mode">
+      When enabled, a guest user will be available in desktop Chrome.
+    </message>
+
     <!-- Toast experiment. -->
     <message name="IDS_TRY_TOAST_SET_DEFAULT" desc="Text of the checkbox to make chrome the default browser">
       Make it my default browser