Lock profile before sign in when force sign in is enabled.

chrome/app/chromium_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 <!-- This file contains definitions of strings that are distribution specific.
 If you update this file, be sure also to update google_chrome_strings.grd. -->
 
 <grit base_dir="." latest_public_release="0" current_release="1"
       output_all_resource_defines="false" source_lang_id="en" enc_check="möl">
   <outputs>
     <output filename="grit/chromium_strings.h" type="rc_header">
       <emit emit_type='prepend'></emit>
     </output>
@@ skipping 762 matching lines @@
           You're now signed in to Chromium! Sync is disabled by your administrator.
         </message>
         <message name="IDS_SYNC_WRONG_EMAIL" desc="Message shown when sync setup failed due to the user entering the wrong email address for sign-in.">
           You were signed in to Chromium as <ph name="USER_EMAIL_ADDRESS">$1<ex>foo@gmail.com</ex></ph>. Please use the same account to sign in again.
         </message>
         <message name="IDS_ONE_CLICK_SIGNIN_CONFIRM_EMAIL_DIALOG_MESSAGE" desc="Error message to display when setting up sync for a second time and the user name is different from the previous user name.">
           Someone previously signed in to Chromium on this computer as <ph name="ACCOUNT_EMAIL_LAST">$1<ex>user@example.com</ex></ph>. If that isn't your account, create a new Chromium user to keep your information separate.
 
 Signing in anyway will merge Chromium information like bookmarks, history, and other settings to <ph name="ACCOUNT_EMAIL_NEW">$2<ex>user@example.com</ex></ph>.
         </message>
+        <message name="IDS_SYNC_USED_PROFILE_ERROR" desc="An error message shown when user tries to sign in to a profile that is used by other user name before.">
+          Someone previously signed in to Chromium on this computer as <ph name="ACCOUNT_EMAIL_LAST">$1<ex>user@example.com</ex></ph>. Please create a new Chromium user to keep your information separate.
+        </message>
       </if>
 
       <!-- Enterprise sign-in profile linking -->
       <if expr="not is_android">
         <message name="IDS_ENTERPRISE_SIGNIN_TITLE" desc="The title of the dialog to confirm linking the browser profile with the signed-in enterprise account">
           Important information regarding your Chromium data
         </message>
         <message name="IDS_ENTERPRISE_SIGNIN_EXPLANATION" desc="The warning message displayed to an enterprise user about to link their profile to their Google account. This message is followed by a 'Learn more' link.">
           You are signing in with a managed account and giving its administrator control over your Chromium profile. Your Chromium data, such as your apps, bookmarks, history, passwords, and other settings will become permanently tied to <ph name="USER_NAME">$1<ex>pat@example.com</ex></ph>. You will be able to delete this data via the Google Accounts Dashboard, but you will not be able to associate this data with another account.
         </message>
@@ skipping 507 matching lines @@
       <message name="IDS_PRIVATE_USER_DATA_INPUT_FUTURE_DESCRIPTION" desc="Description of a security problem where the site collects private user data on an insecure page, which will result in an omnibox warning in future versions of Chromium." translateable="false">
         This page includes a password or credit card input over HTTP. A warning will be added to the URL bar starting in Chromium 56 (Jan 2017).
       </message>
       <message name="IDS_PRIVATE_USER_DATA_INPUT_DESCRIPTION" desc="Description of a security problem where the site collects private user data on an insecure page, which results in an omnibox warning." translateable="false">
         This page includes a password or credit card input over HTTP. A warning has been added to the URL bar.
       </message>
 
     </messages>
   </release>
 </grit>