MD Settings: add empty list message for spell-check edit 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 -->
   <message name="IDS_SETTINGS_ABOUT_PAGE_BROWSER_VERSION" desc="The text label describing the version of the browser, example: Version 57.0.2937.0 (Developer Build) unknown (64-bit)">
     Version <ph name="PRODUCT_VERSION">$1<ex>15.0.865.0</ex></ph> (<ph name="PRODUCT_CHANNEL">$2<ex>Developer Build</ex></ph>) <ph name="PRODUCT_MODIFIER">$3</ph> <ph name="PRODUCT_VERSION_BITS">$4</ph>
   </message>
   <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
@@ skipping 1506 matching lines @@
     </message>
     <message name="IDS_SETTINGS_LANGUAGES_ADD_DICTIONARY_WORD" desc="Label for the text input used to add a new word to the custom spell check dictionary.">
       Add a new word
     </message>
     <message name="IDS_SETTINGS_LANGUAGES_ADD_DICTIONARY_WORD_BUTTON" desc="Button next to the 'add word' text input used to add the word typed by the user to the custom spell check dictionary.">
       Add word
     </message>
     <message name="IDS_SETTINGS_LANGUAGES_DICTIONARY_WORDS" desc="Header for the list of custom dictionary words used for spell check.">
       Custom words
     </message>
+    <message name="IDS_SETTINGS_LANGUAGES_DICTIONARY_WORDS_NONE" desc="Placeholder that is shown when there are no custom words in the list of saved custom words dictionary.">
+      No custom words were found
+    </message>
   </if>
 
   <!-- Privacy Page -->
   <message name="IDS_SETTINGS_PRIVACY" desc="Name of the settings page which allows users to modify privacy and security settings.">
     Privacy and security
   </message>
   <message name="IDS_SETTINGS_LINKDOCTOR_PREF" desc="The documentation string of the 'Use Link Doctor' preference to help with navigation errors.">
     Use a web service to help resolve navigation errors
   </message>
   <if expr="chromeos">
@@ skipping 1280 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>