Implemented declarative redirects to transparent image and empty document.

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

Index: chrome/common/extensions/docs/static/webRequest.html
diff --git a/chrome/common/extensions/docs/static/webRequest.html b/chrome/common/extensions/docs/static/webRequest.html
index ab9f4c9f4ba79d69c27b7807bd6fd80a17fb6aaa..3898a3e0f6b09e9edd0796a418edbebfd8e0279d 100644
--- a/chrome/common/extensions/docs/static/webRequest.html
+++ b/chrome/common/extensions/docs/static/webRequest.html
@@ -96,7 +96,8 @@ event definitions:<br/>
 </dl>
 The web request API guarantees that for each request either
 <code>onCompleted</code> or <code>onErrorOccurred</code> is fired as the final
-event.
+event with one exception: If a request is redirected to a <code>data://</code>
+URL, <code>onBeforeRedirect</code> is the last reported event.
 </p>
 
 <p id="life_cycle_footnote">(*) Note that the web request API presents an