Get rid of {Enable|Disable|ChromeCaptivePortalDetector flag.

chrome/app/chromium_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 <!-- This file contains definitions of strings that are distribution specific.
 These strings will not be translated and only english versions will
 be available for now. -->
 
 <grit base_dir="." latest_public_release="0" current_release="1"
       source_lang_id="en" enc_check="möl">
   <outputs>
     <output filename="grit/chromium_strings.h" type="rc_header">
       <emit emit_type='prepend'></emit>
@@ skipping 689 matching lines @@
       <!-- about:flags -->
       <if expr="not pp_ifdef('chromeos')">
         <message name="IDS_FLAGS_RELAUNCH_NOTICE" desc="Notifies the user that he needs to relaunch Chromium. Shown next to a button that says 'Relaunch Now'.">
           Your changes will take effect the next time you relaunch Chromium.
         </message>
       </if>
       <if expr="pp_ifdef('chromeos')">
         <message name="IDS_FLAGS_RELAUNCH_NOTICE" desc="Notifies the user that he needs to restart Chromium OS. Shown next to a button that says 'Restart Now'.">
           Your changes will take effect the next time you restart your device.
         </message>
-        <message name="IDS_FLAGS_CHROME_CAPTIVE_PORTAL_DETECTOR" desc="Description for the option of Captive Portal detector.">
-          Chromium Captive Portal detector
-        </message>
       </if>
 
       <!-- Obsolete System info bar -->
       <message name="IDS_SYSTEM_OBSOLETE_MESSAGE" desc="Message shown when your OS is no longer supported. This message is followed by a 'Learn more' link.">
          Chromium has stopped updating and no longer supports this version of your operating system.
       </message>
 
       <!-- Google API keys info bar -->
       <message name="IDS_MISSING_GOOGLE_API_KEYS" desc="Message shown when Google API keys are missing. This message is followed by a 'Learn more' link.">
         Google API keys are missing. Some functionality of Chromium will be disabled.
@@ skipping 337 matching lines @@
       <message name="IDS_PROFILE_IN_USE_LINUX" desc="Message shown when the browser cannot start because the profile is in use on a different host.">
         The profile appears to be in use by another Chromium process (<ph name="PROCESS_ID">$1<ex>12345</ex></ph>) on another computer (<ph name="HOST_NAME">$2<ex>example.com</ex></ph>). Chromium has locked the profile so that it doesn't get corrupted. If you are sure no other processes are using this profile, you can unlock the profile and relaunch Chromium.
       </message>
       <message name="IDS_PROFILE_IN_USE_LINUX_RELAUNCH" desc="Text of button in dialog to delete the profile lock file.">
         Unlock Profile and Relaunch
       </message>
 
     </messages>
   </release>
 </grit>