Remove the simplified-fullscreen-ui flag on Android.

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 639 matching lines @@
       </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.">
         Ask before allowing sites to send notifications (recommended)
       </message>
-      <message name="IDS_WEBSITE_SETTINGS_CATEGORY_FULLSCREEN_ASK" desc="Summary text explaining that sites need to ask for permission before going fullscreen and that it is the recommended setting.">
-        Ask first before allowing sites to enter fullscreen (recommended)
-      </message>
       <message name="IDS_WEBSITE_SETTINGS_CATEGORY_CAMERA_ASK" desc="Summary text explaining that sites need to ask for permission before accessing the camera and that it is the recommended setting.">
         Ask first before allowing sites to use your camera (recommended)
       </message>
       <message name="IDS_WEBSITE_SETTINGS_CATEGORY_MIC_ASK" desc="Summary text explaining that sites need to ask for permission before accessing the microphone and that it is the recommended setting.">
         Ask first before allowing sites to use your microphone (recommended)
       </message>
       <message name="IDS_WEBSITE_SETTINGS_PERMISSIONS_ALLOW" desc="Summary text explaining that Chrome will allow a website to access some permission, e.g. JavaScript: allow.">
         Allow
       </message>
       <message name="IDS_WEBSITE_SETTINGS_PERMISSIONS_BLOCK" desc="Summary text explaining that Chrome will block a website from accessing some permission, e.g. JavaScript: block.">
@@ skipping 1766 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>