Update write checks for external extension file on mac.

chrome/common/extensions/docs/external_extensions.html

Index: chrome/common/extensions/docs/external_extensions.html
diff --git a/chrome/common/extensions/docs/external_extensions.html b/chrome/common/extensions/docs/external_extensions.html
index 3bcd7e7efa5f43d63f18d2cf79e6c245bef48417..b406e930a366f2772e95f945b97ce717d9ba53ff 100644
--- a/chrome/common/extensions/docs/external_extensions.html
+++ b/chrome/common/extensions/docs/external_extensions.html
@@ -445,7 +445,7 @@ or <code>/home/share/extension.crx</code>.)
     </dd>
   <dt> Mac OS X: </dt>
     <dd> <code>/Library/Application Support/Google/Chrome/External Extensions/</code> </dd>
-    <p class="note"><b>Note:</b> The external extensions file is read only if every directory in the path is owned by the user <code>root</code>, has the group <code>admin</code>, and is not world readable.  The path must also be free of symbolic links.  These restrictions prevent an unprivileged user from causing extensions to be installed for all users.  See <a href="#troubleshooting">troubleshooting</a> for details.</p>
+    <p class="note"><b>Note:</b> The external extensions file is read only if every directory in the path is owned by the user <code>root</code>, has the group <code>admin</code> or <code>wheel</code>, and is not world writable.  The path must also be free of symbolic links.  These restrictions prevent an unprivileged user from causing extensions to be installed for all users.  See <a href="#troubleshooting">troubleshooting</a> for details.</p>
     <p class="note">
     <b>Note:</b> The above path was added in Chrome 16.  Prior versions used a different path, which is now deprecated:
     <code>/Applications/Google Chrome.app/Contents/Extensions/</code> .</p>