Fix some typos, broken links and other issues in extension docs

chrome/common/extensions/docs/templates/articles/messaging.html

 <h1>Message Passing</h1>
 
 
 <p>
 Since content scripts run in the context of a web page and not the extension,
 they often need some way of communicating with the rest of the extension. For
 example, an RSS reader extension might use content scripts to detect the
 presence of an RSS feed on a page, then notify the background page in order to
 display a page action icon for that page.
 
@@ skipping 136 matching lines @@
       port.postMessage({question: "Madame who?"});
     else if (msg.answer == "Madame... Bovary")
       port.postMessage({question: "I don't get it."});
   });
 });
 </pre>
 
 <p>
 You may want to find out when a connection is closed, for example if you are
 maintaining separate state for each open port. For this you can listen to the
-$ref:runtime.Port
+$ref:runtime.Port.onDisconnect
 event. This event is fired either when the other side of the channel manually
 calls
-$ref:runtime.Port, or when the page
+$ref:runtime.Port.disconnect, or when the page
 containing the port is unloaded (for example if the tab is navigated).
 onDisconnect is guaranteed to be fired only once for any given port.
 
 
 <h2 id="external">Cross-extension messaging</h2>
 <p>
 In addition to sending messages between different components in your
 extension, you can use the messaging API to communicate with other extensions.
 This lets you expose a public API that other extensions can take advantage of.
 
@@ skipping 94 matching lines @@
 <a href="http://src.chromium.org/viewvc/chrome/trunk/src/chrome/common/extensions/docs/examples/api/messaging/">examples/api/messaging</a>
 directory.
 Also see the
 <a href="http://src.chromium.org/viewvc/chrome/trunk/src/chrome/common/extensions/docs/examples/howto/contentscript_xhr">contentscript_xhr</a> example,
 in which a content script and its parent extension exchange messages,
 so that the parent extension can perform
 cross-site requests on behalf of the content script.
 For more examples and for help in viewing the source code, see
 <a href="samples.html">Samples</a>.
 </p>