diff --git a/build/pgo/server-locations.txt b/build/pgo/server-locations.txt
index a93a67fda37..dd59b91069e 100644
--- a/build/pgo/server-locations.txt
+++ b/build/pgo/server-locations.txt
@@ -147,3 +147,8 @@ https://sectest1.example.org:443       privileged
 https://sub.sectest2.example.org:443   privileged
 https://sectest2.example.org:443
 https://sub.sectest1.example.org:443
+
+#
+# Used while testing the url-classifier
+#
+http://malware.com:80  privileged
diff --git a/content/base/src/nsObjectLoadingContent.cpp b/content/base/src/nsObjectLoadingContent.cpp
index c86a414f69b..758d6ffc6ea 100644
--- a/content/base/src/nsObjectLoadingContent.cpp
+++ b/content/base/src/nsObjectLoadingContent.cpp
@@ -1753,7 +1753,7 @@ nsObjectLoadingContent::CheckClassifier(nsIChannel *aChannel)
     do_CreateInstance(NS_CHANNELCLASSIFIER_CONTRACTID, &rv);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  rv = classifier->Start(aChannel);
+  rv = classifier->Start(aChannel, PR_FALSE);
   if (rv == NS_ERROR_FACTORY_NOT_REGISTERED) {
     // no URI classifier, ignore this
     return NS_OK;
diff --git a/content/base/src/nsScriptLoader.cpp b/content/base/src/nsScriptLoader.cpp
index 6f08b65adb2..79417503848 100644
--- a/content/base/src/nsScriptLoader.cpp
+++ b/content/base/src/nsScriptLoader.cpp
@@ -68,6 +68,8 @@
 #include "nsContentErrors.h"
 #include "nsIParser.h"
 #include "nsThreadUtils.h"
+#include "nsIChannelClassifier.h"
+#include "nsDocShellCID.h"
 
 //////////////////////////////////////////////////////////////
 // Per-request data structure
@@ -264,7 +266,21 @@ nsScriptLoader::StartLoad(nsScriptLoadRequest *aRequest, const nsAString &aType)
   rv = NS_NewStreamLoader(getter_AddRefs(loader), this);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  return channel->AsyncOpen(loader, aRequest);
+  rv = channel->AsyncOpen(loader, aRequest);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Check the load against the URI classifier
+  nsCOMPtr<nsIChannelClassifier> classifier =
+    do_CreateInstance(NS_CHANNELCLASSIFIER_CONTRACTID);
+  if (classifier) {
+    rv = classifier->Start(channel, PR_TRUE);
+    if (NS_FAILED(rv)) {
+      channel->Cancel(rv);
+      return rv;
+    }
+  }
+
+  return NS_OK;
 }
 
 PRBool
diff --git a/docshell/base/nsDocShell.cpp b/docshell/base/nsDocShell.cpp
index 4316e5856d8..74312b4700b 100644
--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -7797,7 +7797,7 @@ nsDocShell::CheckClassifier(nsIChannel *aChannel)
     nsRefPtr<nsClassifierCallback> classifier = new nsClassifierCallback();
     if (!classifier) return NS_ERROR_OUT_OF_MEMORY;
 
-    nsresult rv = classifier->Start(aChannel);
+    nsresult rv = classifier->Start(aChannel, PR_FALSE);
     if (rv == NS_ERROR_FACTORY_NOT_REGISTERED ||
         rv == NS_ERROR_NOT_AVAILABLE) {
         // no URI classifier => ignored cases
@@ -9683,10 +9683,12 @@ nsDocShell::IsOKToLoadURI(nsIURI* aURI)
 // nsClassifierCallback
 //*****************************************************************************
 
-NS_IMPL_ISUPPORTS3(nsClassifierCallback,
+NS_IMPL_ISUPPORTS5(nsClassifierCallback,
                    nsIChannelClassifier,
                    nsIURIClassifierCallback,
-                   nsIRunnable)
+                   nsIRunnable,
+                   nsIChannelEventSink,
+                   nsIInterfaceRequestor)
 
 NS_IMETHODIMP
 nsClassifierCallback::Run()
@@ -9711,7 +9713,7 @@ nsClassifierCallback::Run()
 
     // Don't bother to run the classifier on a cached load that was
     // previously classified.
-    if (HasBeenClassified()) {
+    if (HasBeenClassified(channel)) {
         return NS_OK;
     }
 
@@ -9803,10 +9805,10 @@ nsClassifierCallback::MarkEntryClassified(nsresult status)
 }
 
 PRBool
-nsClassifierCallback::HasBeenClassified()
+nsClassifierCallback::HasBeenClassified(nsIChannel *aChannel)
 {
     nsCOMPtr<nsICachingChannel> cachingChannel =
-        do_QueryInterface(mSuspendedChannel);
+        do_QueryInterface(aChannel);
     if (!cachingChannel) {
         return PR_FALSE;
     }
@@ -9862,15 +9864,26 @@ nsClassifierCallback::OnClassifyComplete(nsresult aErrorCode)
 }
 
 NS_IMETHODIMP
-nsClassifierCallback::Start(nsIChannel *aChannel)
+nsClassifierCallback::Start(nsIChannel *aChannel, PRBool aInstallListener)
 {
     mChannel = aChannel;
+
+    if (aInstallListener) {
+        nsresult rv = aChannel->GetNotificationCallbacks
+            (getter_AddRefs(mNotificationCallbacks));
+        NS_ENSURE_SUCCESS(rv, rv);
+
+        rv = aChannel->SetNotificationCallbacks
+            (static_cast<nsIInterfaceRequestor*>(this));
+        NS_ENSURE_SUCCESS(rv, rv);
+    }
+
     return Run();
 }
 
 NS_IMETHODIMP
 nsClassifierCallback::OnRedirect(nsIChannel *aOldChannel,
-                                nsIChannel *aNewChannel)
+                                 nsIChannel *aNewChannel)
 {
     mChannel = aNewChannel;
 
@@ -9900,3 +9913,36 @@ nsClassifierCallback::Cancel()
 
     return NS_OK;
 }
+
+NS_IMETHODIMP
+nsClassifierCallback::OnChannelRedirect(nsIChannel *aOldChannel,
+                                        nsIChannel *aNewChannel,
+                                        PRUint32 aFlags)
+{
+    nsresult rv = OnRedirect(aOldChannel, aNewChannel);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    if (mNotificationCallbacks) {
+        nsCOMPtr<nsIChannelEventSink> sink =
+            do_GetInterface(mNotificationCallbacks);
+        if (sink) {
+            return sink->OnChannelRedirect(aOldChannel, aNewChannel, aFlags);
+        }
+    }
+
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+nsClassifierCallback::GetInterface(const nsIID &aIID, void **aResult)
+{
+    if (aIID.Equals(NS_GET_IID(nsIChannelEventSink))) {
+        NS_ADDREF_THIS();
+        *aResult = static_cast<nsIChannelEventSink *>(this);
+        return NS_OK;
+    } else if (mNotificationCallbacks) {
+        return mNotificationCallbacks->GetInterface(aIID, aResult);
+    } else {
+        return NS_ERROR_NO_INTERFACE;
+    }
+}
diff --git a/docshell/base/nsDocShell.h b/docshell/base/nsDocShell.h
index 5c15c47c1cd..a7622e0044d 100644
--- a/docshell/base/nsDocShell.h
+++ b/docshell/base/nsDocShell.h
@@ -148,6 +148,8 @@ protected:
 class nsClassifierCallback : public nsIChannelClassifier
                            , public nsIURIClassifierCallback
                            , public nsIRunnable
+                           , public nsIChannelEventSink
+                           , public nsIInterfaceRequestor
 {
 public:
     nsClassifierCallback() {}
@@ -157,13 +159,16 @@ public:
     NS_DECL_NSICHANNELCLASSIFIER
     NS_DECL_NSIURICLASSIFIERCALLBACK
     NS_DECL_NSIRUNNABLE
+    NS_DECL_NSICHANNELEVENTSINK
+    NS_DECL_NSIINTERFACEREQUESTOR
 
 private:
     nsCOMPtr<nsIChannel> mChannel;
     nsCOMPtr<nsIChannel> mSuspendedChannel;
+    nsCOMPtr<nsIInterfaceRequestor> mNotificationCallbacks;
 
     void MarkEntryClassified(nsresult status);
-    PRBool HasBeenClassified();
+    PRBool HasBeenClassified(nsIChannel *aChannel);
 };
 
 //*****************************************************************************
diff --git a/docshell/base/nsIChannelClassifier.idl b/docshell/base/nsIChannelClassifier.idl
index 0c19c3c1dd6..6bd48b7e17d 100644
--- a/docshell/base/nsIChannelClassifier.idl
+++ b/docshell/base/nsIChannelClassifier.idl
@@ -46,7 +46,7 @@ interface nsIChannel;
  * URI classifier service, and cancels the channel before OnStartRequest
  * if it is found on a blacklist.
  */
-[scriptable, uuid(d17f8f74-d403-4dea-b124-3ace5dbe44dc)]
+[scriptable, uuid(1481c5b5-9f6e-4995-8fe3-2aad5c06440d)]
 interface nsIChannelClassifier : nsISupports
 {
   /**
@@ -59,10 +59,18 @@ interface nsIChannelClassifier : nsISupports
    * If there is no URI classifier service, NS_ERROR_FACTORY_NOT_REGISTERED
    * will be returned.
    *
+   * This method must be called immediately after AsyncOpen() has been called
+   * on the channel.
+   *
    * @param aChannel
    *        The channel to suspend.
+   * @param aInstallListener
+   *        If true, the classifier will install notification
+   *        callbacks to listen for redirects.  The classifier will
+   *        pass all notifications on to the channel's existing
+   *        notification callbacks.
    */
-  void start(in nsIChannel aChannel);
+  void start(in nsIChannel aChannel, in boolean aInstallListener);
 
   /**
    * Notify the classifier that the channel was redirected.  The new channel
diff --git a/layout/style/nsCSSLoader.cpp b/layout/style/nsCSSLoader.cpp
index deffc33ff3d..112379b5740 100644
--- a/layout/style/nsCSSLoader.cpp
+++ b/layout/style/nsCSSLoader.cpp
@@ -79,6 +79,8 @@
 #include "nsICSSImportRule.h"
 #include "nsThreadUtils.h"
 #include "nsGkAtoms.h"
+#include "nsDocShellCID.h"
+#include "nsIChannelClassifier.h"
 
 #ifdef MOZ_XUL
 #include "nsXULPrototypeCache.h"
@@ -1461,6 +1463,19 @@ CSSLoaderImpl::LoadSheet(SheetLoadData* aLoadData, StyleSheetState aSheetState)
     return rv;
   }
 
+  // Check the load against the URI classifier
+  nsCOMPtr<nsIChannelClassifier> classifier =
+    do_CreateInstance(NS_CHANNELCLASSIFIER_CONTRACTID);
+  if (classifier) {
+    rv = classifier->Start(channel, PR_TRUE);
+    if (NS_FAILED(rv)) {
+      LOG_ERROR(("  Failed to classify URI"));
+      SheetComplete(aLoadData, rv);
+      channel->Cancel(rv);
+      return rv;
+    }
+  }
+
   if (!mLoadingDatas.Put(&key, aLoadData)) {
     LOG_ERROR(("  Failed to put data in loading table"));
     aLoadData->mIsCancelled = PR_TRUE;
diff --git a/toolkit/components/url-classifier/tests/Makefile.in b/toolkit/components/url-classifier/tests/Makefile.in
index 1d9e6f6e406..a0d1ed0c3dc 100644
--- a/toolkit/components/url-classifier/tests/Makefile.in
+++ b/toolkit/components/url-classifier/tests/Makefile.in
@@ -55,6 +55,10 @@ REQUIRES = \
 	necko \
 	$(NULL)
 
+# mochitest tests
+DIRS += mochitest \
+	$(NULL)
+
 # xpcshell tests
 XPCSHELL_TESTS=unit
 
diff --git a/toolkit/components/url-classifier/tests/mochitest/Makefile.in b/toolkit/components/url-classifier/tests/mochitest/Makefile.in
new file mode 100644
index 00000000000..e5d1e93c594
--- /dev/null
+++ b/toolkit/components/url-classifier/tests/mochitest/Makefile.in
@@ -0,0 +1,57 @@
+#
+# ***** BEGIN LICENSE BLOCK *****
+# Version: MPL 1.1/GPL 2.0/LGPL 2.1
+#
+# The contents of this file are subject to the Mozilla Public License Version
+# 1.1 (the "License"); you may not use this file except in compliance with
+# the License. You may obtain a copy of the License at
+# http://www.mozilla.org/MPL/
+#
+# Software distributed under the License is distributed on an "AS IS" basis,
+# WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+# for the specific language governing rights and limitations under the
+# License.
+# # The Original Code is mozilla.org code.
+#
+# The Initial Developer of the Original Code is
+# Mozilla Corporation.
+# Portions created by the Initial Developer are Copyright (C) 2008
+# the Initial Developer. All Rights Reserved.
+#
+# Contributor(s):
+#
+# Alternatively, the contents of this file may be used under the terms of
+# either of the GNU General Public License Version 2 or later (the "GPL"),
+# or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+# in which case the provisions of the GPL or the LGPL are applicable instead
+# of those above. If you wish to allow use of your version of this file only
+# under the terms of either the GPL or the LGPL, and not to allow others to
+# use your version of this file under the terms of the MPL, indicate your
+# decision by deleting the provisions above and replace them with the notice
+# and other provisions required by the GPL or the LGPL. If you do not delete
+# the provisions above, a recipient may use your version of this file under
+# the terms of any one of the MPL, the GPL or the LGPL.
+#
+# ***** END LICENSE BLOCK *****
+
+DEPTH		= ../../../../..
+topsrcdir	= @top_srcdir@
+srcdir		= @srcdir@
+VPATH		= @srcdir@
+relativesrcdir  = toolkit/components/url-classifier/tests/mochitest
+
+MODULE = test_url-classifier
+
+include $(DEPTH)/config/autoconf.mk
+include $(topsrcdir)/config/rules.mk
+
+_TEST_FILES = \
+		test_classifier.html \
+		classifierFrame.html \
+		evil.js \
+		evil.css \
+		import.css \
+		$(NULL)
+
+libs:: $(_TEST_FILES)
+	$(INSTALL) $(foreach f,$^,"$f") $(DEPTH)/_tests/testing/mochitest/tests/$(relativesrcdir)
diff --git a/toolkit/components/url-classifier/tests/mochitest/classifierFrame.html b/toolkit/components/url-classifier/tests/mochitest/classifierFrame.html
new file mode 100644
index 00000000000..f3f72daeff0
--- /dev/null
+++ b/toolkit/components/url-classifier/tests/mochitest/classifierFrame.html
@@ -0,0 +1,34 @@
+<html> <head>
+<title></title>
+</head>
+
+<script type="text/javascript">
+var scriptItem = "untouched";
+
+function checkLoads() {
+  // Make sure the javascript did not load.
+  window.parent.is(scriptItem, "untouched", "Should not load bad javascript");
+
+  // Make sure the css did not load.
+  var elt = document.getElementById("styleCheck");
+  var style = document.defaultView.getComputedStyle(elt, "");
+  window.parent.isnot(style.visibility, "hidden", "Should not load bad css");
+
+  window.parent.SimpleTest.finish();
+}
+
+</script>
+
+<!-- Try loading from a malware javascript URI -->
+<script type="text/javascript" src="http://malware.com/tests/toolkit/components/url-classifier/tests/mochitest/evil.js"></script>
+
+<!-- Try loading from a malware css URI
+<link rel="stylesheet" type="text/css" href="http://malware.com/tests/toolkit/components/url-classifier/tests/mochitest/evil.css"></link>
+
+<!-- Try loading a marked-as-malware css through an @import from a clean URI -->
+<link rel="stylesheet" type="text/css" href="import.css"></link>
+
+<body onload="checkLoads()">
+The following should not be hidden:
+<div id="styleCheck">STYLE TEST</div>
+</body> </html>
diff --git a/toolkit/components/url-classifier/tests/mochitest/evil.css b/toolkit/components/url-classifier/tests/mochitest/evil.css
new file mode 100644
index 00000000000..f6f08d7c5cd
--- /dev/null
+++ b/toolkit/components/url-classifier/tests/mochitest/evil.css
@@ -0,0 +1 @@
+#styleCheck { visibility: hidden; }
\ No newline at end of file
diff --git a/toolkit/components/url-classifier/tests/mochitest/evil.js b/toolkit/components/url-classifier/tests/mochitest/evil.js
new file mode 100644
index 00000000000..27f2e8c43d5
--- /dev/null
+++ b/toolkit/components/url-classifier/tests/mochitest/evil.js
@@ -0,0 +1 @@
+scriptItem = "loaded malware javascript!";
diff --git a/toolkit/components/url-classifier/tests/mochitest/import.css b/toolkit/components/url-classifier/tests/mochitest/import.css
new file mode 100644
index 00000000000..91f5fbf1432
--- /dev/null
+++ b/toolkit/components/url-classifier/tests/mochitest/import.css
@@ -0,0 +1 @@
+@import url("http://malware.com/tests/docshell/test/classifierBad.css");
diff --git a/toolkit/components/url-classifier/tests/mochitest/test_classifier.html b/toolkit/components/url-classifier/tests/mochitest/test_classifier.html
new file mode 100644
index 00000000000..3378f2431e1
--- /dev/null
+++ b/toolkit/components/url-classifier/tests/mochitest/test_classifier.html
@@ -0,0 +1,81 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test the URI Classifier</title>
+  <script type="text/javascript" src="/MochiKit/MochiKit.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<p id="display"></p>
+<div id="content" style="display: none">
+</div>
+<pre id="test">
+
+<script class="testbody" type="text/javascript">
+
+netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+
+// Add some URLs to the malware database.
+var testData = "malware.com/"
+var testUpdate =
+  "n:1000\ni:test-malware-simple\nad:1\n" +
+  "a:524:32:" + testData.length + "\n" +
+  testData;
+
+var dbService = Cc["@mozilla.org/url-classifier/dbservice;1"]
+                .getService(Ci.nsIUrlClassifierDBService);
+
+var numTries = 10;
+
+function doUpdate(update) {
+  var listener = {
+    QueryInterface: function(iid)
+    {
+      if (iid.equals(Ci.nsISupports) ||
+          iid.equals(Ci.nsIUrlClassifierUpdateObserver))
+        return this;
+      throw Cr.NS_ERROR_NO_INTERFACE;
+    },
+
+    updateUrlRequested: function(url) { },
+    streamFinished: function(status) { },
+    updateError: function(errorCode) {
+      ok(false, "Couldn't update classifier.");
+      SimpleTest.finish();
+    },
+    updateSuccess: function(requestedTimeout) {
+      document.getElementById("testFrame").src = "classifierFrame.html";
+    }
+  };
+
+  netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
+
+  try {
+    dbService.beginUpdate(listener,
+                          "test-malware-simple", "");
+    dbService.beginStream("", "");
+    dbService.updateStream(update);
+    dbService.finishStream();
+    dbService.finishUpdate();
+  } catch(ex) {
+    // The DB service might already be updating.  Try again after a 5 seconds...
+    if (--numTries != 0) {
+      setTimeout(function() { doUpdate(update) }, 5000);
+      return;
+    }
+    throw ex;
+  }
+}
+
+doUpdate(testUpdate);
+
+SimpleTest.waitForExplicitFinish();
+
+</script>
+</pre>
+<iframe id="testFrame" onload=""></iframe>
+</body>
+</html>