Implement restart-required message on Linux.

chrome/app/chromium_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 <!-- This file contains definitions of strings that are distribution specific.
 If you update this file, be sure also to update google_chrome_strings.grd. -->
 
 <grit base_dir="." latest_public_release="0" current_release="1"
       output_all_resource_defines="false" source_lang_id="en" enc_check="möl">
   <outputs>
     <output filename="grit/chromium_strings.h" type="rc_header">
       <emit emit_type='prepend'></emit>
     </output>
@@ skipping 1190 matching lines @@
       </message>
       <message name="IDS_PAGE_INFO_SECURITY_TAB_SECURE_IDENTITY_CT_INVALID" desc="The text of the identity section when the page is secure, but it contains a Signed Certificate Timestamp from a known Certificate Transparency log that failed to verify.">
         Chromium verified that <ph name="ISSUER">$1<ex>VeriSign</ex></ph> issued this website's certificate. The server supplied Certificate Transparency information, but it was invalid.
       </message>
 
       <!-- Desktop Capture -->
       <message name="IDS_DESKTOP_MEDIA_PICKER_SOURCE_TYPE_TAB" desc="Text for the button on the window picker dialog, clicking which takes one to tab sharing">
         Chromium Tab
       </message>
 
+      <!-- Plugin Placeholders -->
+      <message name="IDS_PLUGIN_RESTART_REQUIRED" desc="The placeholder text for a plugin that can't be loaded until the browser is restarted.">
+        Restart Chromium to enable <ph name="PLUGIN_NAME">$1<ex>Flash</ex></ph>
+      </message>
+
       <!-- Runtime permission strings -->
       <if expr="is_android">
         <message name="IDS_INFOBAR_MISSING_CAMERA_PERMISSION_TEXT" desc="Text shown in an infobar when a website has requested access to the camera capabilities, but Chrome is missing the Android camera permission.">
           Chromium needs camera access to share it with this site.
         </message>
         <message name="IDS_INFOBAR_MISSING_MICROPHONE_PERMISSION_TEXT" desc="Text shown in an infobar when a website has requested access to the microphone capabilities, but Chrome is missing the Android microphone permission.">
           Chromium needs microphone access to share it with this site.
         </message>
         <message name="IDS_INFOBAR_MISSING_LOCATION_PERMISSION_TEXT" desc="Text shown in an infobar when a website has requested access to the location capabilities, but Chrome is missing the Android location permission.">
           Chromium needs location access to share it with this site.
@@ skipping 63 matching lines @@
           Pin Chromium to your taskbar
         </message>
         <message name="IDS_WIN10_WELCOME_SELECT" desc="An instruction asking the user to select Chromium from an external list of apps.">
           Select <ph name="SMALL_PRODUCT_LOGO">&lt;div class="logo-small"&gt;&lt;/div&gt;</ph> <ph name="BEGIN_BOLD">&lt;strong&gt;</ph>Chromium<ph name="END_BOLD">&lt;/strong&gt;</ph>
         </message>
       </if>
 
     </messages>
   </release>
 </grit>