Remove support for the keygen tag

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 578 matching lines @@
       </message>
       <message name="IDS_ALLOW_THIRD_PARTY_COOKIES_TITLE" desc="Title for Allow Third Party Cookies preference">
         Allow third-party cookies
       </message>
       <message name="IDS_ALLOW_THIRD_PARTY_COOKIES_SUMMARY" desc="Summary text for Allow Third Party Cookies preference">
         Third-party websites can save and read cookie data
       </message>
       <message name="IDS_JAVASCRIPT_PERMISSION_TITLE" desc="Title of the permission to run javascript [CHAR-LIMIT=32]">
         JavaScript
       </message>
-      <message name="IDS_KEYGEN_PERMISSION_TITLE" desc="Title of the permission to allow a form to perform client-side key generation [CHAR-LIMIT=32]">
-        Key generation
-      </message>
       <message name="IDS_MEDIA_PERMISSION_TITLE" desc="Title of the menu containing the media permissions [CHAR-LIMIT=32]">
         Media
       </message>
       <message name="IDS_POPUP_PERMISSION_TITLE" desc="Title of the permission to display pop-up windows [CHAR-LIMIT=32]">
         Pop-ups
       </message>
       <message name="IDS_PUSH_NOTIFICATIONS_PERMISSION_TITLE" desc="Title for the permission for showing push notifications [CHAR-LIMIT=32]">
         Notifications
       </message>
       <message name="IDS_ENABLE_NOTIFICATIONS_VIBRATE_TITLE" desc="Title for the preference to enable vibration for notifications">
@@ skipping 2267 matching lines @@
       </message>
       <message name="IDS_KEYBOARD_SHORTCUT_CHROME_FEATURE_GROUP_HEADER" desc="A text label that appears above a list of shortcuts that are related to the Chrome app features. This group is part of several groups of keyboard shortcuts all shown in a dialog.">
         Google Chrome feature shortcuts
       </message>
       <message name="IDS_KEYBOARD_SHORTCUT_WEBPAGE_GROUP_HEADER" desc="A text label that appears above a list of shortcuts that are related to manipulation of the current tab window. This group is part of several groups of keyboard shortcuts all shown in a dialog.">
         Webpage shortcuts
       </message>
     </messages>
   </release>
 </grit>