Support chrome-extension:// scheme in URLPattern.

chrome/common/extensions/docs/static/webRequest.html

 <div id="pageData-name" class="pageData">WebRequest API</div>
 
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 <p id="classSummary">
 Use the <code>chrome.webRequest</code> module to intercept, block,
 or modify requests in-flight. This module is still experimental. For
 information on how to use experimental APIs, see the
 <a href="experimental.html">chrome.experimental.* APIs</a> page.
 </p>
 
@@ skipping 177 matching lines @@
 <p>Depending on the specific signal, <code>opt_extraInfoSpec</code> may contain
 further strings that indicate that specific information shall be passed to the
 extension. This is used to provide detailed information on requests data only if
 explicitly requested.</p>
 
 <p>The optional <a href="#type-RequestFilter">RequestFilter</a>
 <code>opt_filter</code> allows to limit the requests for which events are
 triggered in various dimensions:
 <dl>
   <dt>URLs</dt>
-  <dd>URL patterns like <code>*://www.google.com/foo*bar</code>.</dd>
+  <dd><a href="match_patterns.html">URL patterns</a> like
+  <code>*://www.google.com/foo*bar</code>.</dd>
   <dt>Types</dt>
   <dd>Request types like <code>main_frame</code> (a document that is loaded for
   a top-level frame), <code>sub_frame</code> (a document that is loaded for an
   embedded frame), <code>image</code> (an image on a web site) and others. See
   <a href="#type-RequestFilter">RequestFilter</a>.</dd>
   <dt>Tab IDs</dt>
   <dd>The ID that identifies a specific tab in a window.</dd>
   <dt>Window IDs</dt>
   <dd>The ID that identifies a specific window.</dd>
 </p>
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     // Attention: The frameUrl can be undefined in some cases. Requests may not
     // originate from a frame (e.g. requests from extensions or shared workers).
   });
 
 chrome.windows.onRemoved.addListener(
   function(windowId) {delete frameUrl[windowId];}
   );
 </pre>
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