Use a placeholder instead of the default plugin for missing plug-ins on Mac and Linux.

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index c61c96d1742787ed9af96961e2c1e5c9c3a4da06..6b9900ab0dfe69723f40db246497df1845b79b94 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -4734,6 +4734,9 @@ Keep your key file in a safe place. You will need it to create new versions of y
       <message name="IDS_PLUGIN_NOT_AUTHORIZED" desc="The placeholder text for a plug-in that requires user permission to run.">
         The <ph name="PLUGIN_NAME">$1<ex>Java</ex></ph> plug-in needs your permission to run.
       </message>
+      <message name="IDS_PLUGIN_NOT_FOUND" desc="The placeholder text for a plug-in that is not installed.">
+        No plug-in available to display this content.
+      </message>
 
       <!-- Session Crashed Info Bar-->
       <message name="IDS_SESSION_CRASHED_VIEW_RESTORE_BUTTON" desc="Title of the restore button in the session crashed view.">