Bug 142590 Add "Do Not Edit" warning to prefs.js

patch by stevechapel@earthlink.net r=ccarlen sr=rbs

modules/libpref/src/nsPrefService.cpp

@@ -348,11 +348,28 @@ nsresult nsPrefService::UseUserPrefFile()
 
 nsresult nsPrefService::WritePrefFile(nsIFile* aFile)
 {
-  const char                outHeader[] = "# Mozilla User Preferences" 
-                                          NS_LINEBREAK 
-                                          "// This is a generated file!" 
-                                          NS_LINEBREAK 
-                                          NS_LINEBREAK;
+  const char                outHeader[] =
+    "# Mozilla User Preferences"
+    NS_LINEBREAK
+    NS_LINEBREAK
+    "/* Do not edit this file."
+    NS_LINEBREAK
+    " *"
+    NS_LINEBREAK
+    " * If you make changes to this file while the browser is running,"
+    NS_LINEBREAK
+    " * the changes will be overridden when the browser exits."
+    NS_LINEBREAK
+    " *"
+    NS_LINEBREAK
+    " * To make a manual change to preferences, you can visit the URL about:config"
+    NS_LINEBREAK
+    " * For more information, see http://www.mozilla.org/unix/customizing.html#prefs"
+    NS_LINEBREAK
+    " */"
+    NS_LINEBREAK
+    NS_LINEBREAK;
+
   nsCOMPtr<nsIOutputStream> outStream;
   PRUint32                  writeAmount;
   nsresult                  rv;