Implement extension controlled indicators, starting with New Tab page

chrome/app/settings_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Settings-specific strings (included from generated_resources.grd). -->
 <grit-part>
   <!-- About Page -->
   <if expr="chromeos">
     <message name="IDS_SETTINGS_ABOUT_PAGE_DETAILED_BUILD_INFO" desc="Label describing the section that shows detailed information about the current Chrome build.">
       Detailed build information
     </message>
     <message name="IDS_SETTINGS_ABOUT_PAGE_ARC_VERSION" desc="Label for ARC version">
       ARC Version
@@ skipping 236 matching lines @@
   <if expr="not chromeos">
     <message name="IDS_SETTINGS_RESTART" desc="Text for a button that will restart Chrome.">
       Relaunch
     </message>
   </if>
   <if expr="chromeos">
     <message name="IDS_SETTINGS_RESTART" desc="Text for a button that will restart ChromeOS.">
       Restart
     </message>
   </if>
+  <message name="IDS_SETTINGS_CONTROLLED_BY_EXTENSION" desc="Label text of an indicator that a setting's value is being controlled by an extension.">
+    <ph name="NAME">$1<ex>Adblocker plusplus</ex></ph> is controlling this setting
+  </message>
 
   <!-- Passwords and Autofill Page -->
   <message name="IDS_SETTINGS_OVERFLOW_MENU" desc="Alt text for the overflow button on a list item. Triggers a context menu when clicked.">
     Menu
   </message>
   <message name="IDS_SETTINGS_PASSWORDS_AND_AUTOFILL_PAGE_TITLE" desc="Name of the settings page which allows managing passwords and autofill settings.">
     Passwords and forms
   </message>
   <message name="IDS_SETTINGS_AUTOFILL" desc="Name for the autofill section and toggle.">
     Autofill settings
@@ skipping 2390 matching lines @@
       System
     </message>
     <message name="IDS_SETTINGS_SYSTEM_HARDWARE_ACCELERATION_LABEL" desc="Label for the checkbox that forces Chrome to render via hardware acceleration (GPU) when available.">
       Use hardware acceleration when available
     </message>
     <message name="IDS_SETTINGS_SYSTEM_PROXY_SETTINGS_BUTTON" desc="Text for the button that changes a user's network proxy settings.">
       Change proxy settings
     </message>
   </if>
 </grit-part>