Support also excluding content types in declarative webrequest conditions.

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

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 <h2 id="notes">Notes</h2>
 
 <p>
 Use the <code>chrome.declarativeWebRequest</code> module to intercept, block, or
 modify requests in-flight. It is significantly faster than the <a
   href="webRequest.html"><code>chrome.webRequest</code> API</a> because you can
 register rules that are evaluated in the browser rather than the
 JavaScript engine which reduces roundtrip latencies and allows for very high
@@ skipping 31 matching lines @@
 The Declarative Web Request API supports a single type of match criteria, the
 <code>RequestMatcher</code>. The <code>RequestMatcher</code> matches network
 requests if and only if all listed criteria are met. The following
 <code>RequestMatcher</code> would match a network request when the user enters
 "http://www.example.com" in the URL bar:
 </p>
 
 <pre>
 var matcher = new chrome.declarativeWebRequest.RequestMatcher({
   url: { hostSuffix: 'example.com', schemes: ['http'] },
-  resourceType: 'main_frame'
+  resourceType: ['main_frame']
   });
 </pre>
 
 <p>
 Requests to "https://www.example.com" would be rejected by the
 <code>RequestMatcher</code> due to the scheme. Also all requests for an embedded
 iframe would be rejected due to the <code>resourceType</code>.
 </p>
 
 <p class="note">
@@ skipping 51 matching lines @@
 <h2 id="TODO">Todo</h2>
 <ul>
   <li>Explain precedences, once we can ignore rules based on their priority
   (e.g. how can I cancel all requests except for a specific whitelist?)
   <li>Explain when conditions can be evaluated, when actions can be executed,
   and when rules can be executed (e.g. you cannot cancel a request when you
   have received the response already)
 </ul>
 
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