Polished on side-loaded extension install alert.

chrome/app/chromium_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 <!-- This file contains definitions of strings that are distribution specific.
 These strings will not be translated and only english versions will
 be available for now. -->
 
 <grit base_dir="." latest_public_release="0" current_release="1"
       source_lang_id="en" enc_check="möl">
   <outputs>
     <output filename="grit/chromium_strings.h" type="rc_header">
       <emit emit_type='prepend'></emit>
@@ skipping 587 matching lines @@
           Chromium is up to date (<ph name="VERSION">$1<ex>0.1.131</ex></ph>)
         </message>
       </if>
 
       <!-- Extension/App install prompt -->
       <message name="IDS_EXTENSION_INLINE_INSTALL_PROMPT_TITLE" desc="Titlebar of the extension or app inline installation prompt window">
         Add to Chromium
       </message>
 
       <!-- Extension alerts. -->
-      <message name="IDS_EXTENSION_ALERT_ITEM_EXTERNAL" desc="A statement that an external extension has been newly installed. End users have no idea what an 'external' extension is, so we simply call them extensions.">
-The extension "<ph name="EXTENSION_NAME">$1<ex>Gmail Checker</ex></ph>" has been added to Chromium.
+      <message name="IDS_EXTENSION_ALERT_ITEM_EXTERNAL" desc="A statement that an external extension has been newly installed. End users have no idea what an 'external' extension is, so we simply call them extensions. The trailing character must be a newline.">
+The extension "<ph name="EXTENSION_NAME">$1<ex>Gmail Checker</ex></ph>" has been added.
+
 '''
       </message>
 
       <!-- Extension installed bubble -->
       <message name="IDS_EXTENSION_INSTALLED_HEADING" desc="First line in the content area of the extension installed bubble. Instructs that the extension was installed.">
         <ph name="EXTENSION_NAME">$1<ex>Gmail Checker</ex></ph> has been added to Chromium.
       </message>
 
       <!-- chrome://settings/extensions page -->
       <message name="IDS_EXTENSIONS_INCOGNITO_WARNING" desc="Warns the user that Chromium cannot prevent extensions from recording history in incognito mode. Displayed in extensions management UI after an extension is selected to be run in incognito mode.">
@@ skipping 76 matching lines @@
         Chromium Autofill settings
       </message>
 
       <!-- Web Intents -->
       <message name="IDS_INTENT_PICKER_INSTALL_EXTENSION" desc="Text on the button in the web intent picker that installs an extension then uses the extension as an intent service.">
         Add to Chromium
       </message>
     </messages>
   </release>
 </grit>