Disable the autoplay setting entry when Data Saver is ON.

chrome/android/java/strings/android_chrome_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 
 <!-- android_chrome_strings.grd contains strings for Chrome for Android.
 
 FAQ:
   - How do I add, change, or remove a string?
       Just update this file.
   - Translations will happen automatically??
       Yes, indeed. Just add your string before the branch point and
       make the description good.
@@ skipping 651 matching lines @@
       </message>
       <message name="IDS_WEBSITE_SETTINGS_CATEGORY_ALLOWED_RECOMMENDED" desc="Summary text explaining that a permission is allowed, which is the recommended setting.">
         Allowed (recommended)
       </message>
       <message name="IDS_WEBSITE_SETTINGS_CATEGORY_COOKIE_ALLOWED" desc="Summary text explaining that sites are allowed to use cookies and that it is the recommended setting.">
         Allow sites to save and read cookie data (recommended)
       </message>
       <message name="IDS_WEBSITE_SETTINGS_CATEGORY_AUTOPLAY_ALLOWED" desc="Summary text explaining that sites are allowed to automatically play muted videos and that it is the recommended setting.">
         Allow sites to automatically play muted videos (recommended)
       </message>
+      <message name="IDS_WEBSITE_SETTINGS_CATEGORY_AUTOPLAY_DISABLED_DATA_SAVER" desc="Summary text explaining that autoplay setting is unavailable when Data Saver is turned on.">
+        Unavailable when Data Saver is turned on
+      </message>
       <message name="IDS_WEBSITE_SETTINGS_CATEGORY_JAVASCRIPT_ALLOWED" desc="Summary text explaining that sites are allowed to run Javascript and that it is the recommended setting.">
         Allow sites to run JavaScript (recommended)
       </message>
       <message name="IDS_WEBSITE_SETTINGS_CATEGORY_POPUPS_BLOCKED" desc="Summary text explaining that sites are blocked from showing popups and that it is the recommended setting.">
         Block sites from showing pop-ups (recommended)
       </message>
       <message name="IDS_WEBSITE_SETTINGS_CATEGORY_LOCATION_ASK" desc="Summary text explaining that sites need to ask for permission before knowing location and that it is the recommended setting.">
         Ask before allowing sites to know your location (recommended)
       </message>
       <message name="IDS_WEBSITE_SETTINGS_CATEGORY_NOTIFICATIONS_ASK" desc="Summary text explaining that sites need to ask for permission before sending notifications and that it is the recommended setting.">
@@ skipping 1942 matching lines @@
       <!-- Migration strings -->
       <message name="IDS_TAB_SWITCHER_CALLOUT_HEADER" desc="Header for the Tab Switcher callout.">
         Quickly switch tabs
       </message>
       <message name="IDS_TAB_SWITCHER_CALLOUT_BODY" desc="Indicates that clicking the tab switcher button gives you quick access to your tabs.">
         Tap this button for quick access to your tabs.
       </message>
     </messages>
   </release>
 </grit>