Add context menu when long press on a reading list entry

ios/chrome/app/strings/ios_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 
 <!--
 This file contains definition of resources that will be translated for each
 locale.  The strings in this file are specific to iOS.
 -->
 
 <grit base_dir="." latest_public_release="0" current_release="1"
       output_all_resource_defines="false" source_lang_id="en" enc_check="möl">
   <outputs>
@@ skipping 1053 matching lines @@
       </message>
       <message name="IDS_IOS_READING_LIST_ACCESSIBILITY_STATE_DOWNLOADED" desc="Accessibility label for the offline status of the reading list entry. Read by Text To Speech.">
         Available offline
       </message>
       <message name="IDS_IOS_READING_LIST_ACCESSIBILITY_STATE_NOT_DOWNLOADED" desc="Accessibility label for the offline status of the reading list entry. Read by Text To Speech.">
         Not available offline
       </message>
       <message name="IDS_IOS_READING_LIST_CANCEL_BUTTON" desc="Label of the button to stop editing the reading list entries (delete, mark as read/unread) [Length: 25em]" meaning="Stop editing. [Length: 25em]">
         Cancel
       </message>
+      <message name="IDS_IOS_READING_LIST_CONTENT_CONTEXT_OFFLINE" desc="Title of the button to display the Offline version instead of the Online one.">
+        View Offline Version

[stkhapugin, 2017/01/30 10:34:53]

Please add a length in em

[gambard, 2017/01/31 09:35:40]

Done.

+      </message>
       <message name="IDS_IOS_READING_LIST_DELETE_ALL_READ_BUTTON" desc="Label of the button to delete all the reading list entries read [Length: 25em]" meaning="Delete all the read entries. [Length: 25em]">
         Delete Read
       </message>
       <message name="IDS_IOS_READING_LIST_DELETE_BUTTON" desc="Label of the button to delete the reading list entries [Length: 25em]" meaning="Delete the selected entries. [Length: 25em]">
         Delete
       </message>
       <message name="IDS_IOS_READING_LIST_DONE_BUTTON" desc="Label of the button to dismiss reading list dialog">
         Done
       </message>
       <message name="IDS_IOS_READING_LIST_EDIT_BUTTON" desc="Label of the button to edit the reading list entries (delete, mark as read/unread) [Length: 20em]" meaning="Start editing the reading list entries. [Length: 20em]">
@@ skipping 476 matching lines @@
       </message>
       <message name="IDS_IOS_VOICE_SEARCH_SETTING_TITLE" desc="The title for Voice Search setting [Length: 29em] [iOS only]">
         Voice Search
       </message>
       <message name="IDS_IOS_VOICE_SEARCH_SETTING_TTS" desc="The label for setting switch enabling text-to-speech response after voice search [Length: 29em] [iOS only]">
         Speak Answers Back
       </message>
     </messages>
   </release>
 </grit>