Update the error message in the Files app via Downloads panel.

chrome/app/chromeos_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <!-- ChromeOS-specific strings (included from generated_resources.grd).
      Everything in this file is wrapped in <if expr="chromeos">. -->
 <grit-part>
   <message name="IDS_EMPTY_STRING" desc="Empty string, exist only to make code generic. No translation required.">
   </message>
   <message name="IDS_CHROMEBOOK" desc="The localized name for Chromebook.">
     Chromebook
   </message>
   <message name="IDS_CHROMEBOX" desc="The localized name for Chromebox">
@@ skipping 831 matching lines @@
   <message name="IDS_FILE_BROWSER_GLINK_DOCUMENT_FILE_TYPE" desc="Google Drive link file type">
     Google Drive link
   </message>
 
   <message name="IDS_FILE_BROWSER_ERROR_VIEWING_FILE_TITLE" desc="Title of error message propmt when user attempts to open a non-supported file in file browser.">
     <ph name="FILENAME">$1</ph>
   </message>
   <message name="IDS_FILE_BROWSER_ERROR_VIEWING_FILE" desc="Error message when user attempts to open a non-supported file in the Files app via Downloads panel.">
     This file type is not supported. Please visit the Chrome Web Store to find an app that can open this type of file.
   </message>
+  <message name="IDS_FILE_BROWSER_ERROR_VIEWING_FILE_FOR_DMG" desc="Error message when user attempts to open a dmg file in the Files app via Downloads panel.">
+    This file is designed for a computer using Macintosh software. This is not compatible with your device which runs Chrome OS. Please search the Chrome Web Store for a suitable replacement app.
+  </message>
+  <message name="IDS_FILE_BROWSER_ERROR_VIEWING_FILE_FOR_EXECUTABLE" desc="Error message when user attempts to open a exe file in the Files app via Downloads panel.">
+    This file is designed for a PC using Windows software. This is not compatible with your device which runs Chrome OS. Please search the Chrome Web Store for a suitable replacement app.
+  </message>
   <message name="IDS_FILE_BROWSER_ERROR_UNRESOLVABLE_FILE" desc="Error message when the file attempted to open from Downloads panel was not found under paths managed by file manager.">
     This file has wandered off somewhere. Please check your download location setting and try again.
   </message>
   <message name="IDS_FILE_BROWSER_AUDIO_PLAYER_TITLE" desc="Title of the Audio Player window.">
     Audio Player
   </message>
   <message name="IDS_FILE_BROWSER_AUDIO_PLAYER_DEFAULT_ARTIST" desc="In the Audio Player window, default artist name used when artist name is unknown.">
     Unknown Artist
   </message>
 
@@ skipping 4945 matching lines @@
   <message name="IDS_SET_TIME_BUTTON_CLOSE" desc="Text for the button to close the window.">
     Done
   </message>
   <message name="IDS_SET_TIME_DATE_LABEL" desc="Label for the date input element.">
     System date
   </message>
   <message name="IDS_SET_TIME_TIME_LABEL" desc="Label for the time input element.">
     System time
   </message>
 </grit-part>