diff --git a/mozilla/content/base/public/nsIXMLHttpRequest.idl b/mozilla/content/base/public/nsIXMLHttpRequest.idl
index 7c91d3401f0..a78255b70f3 100644
--- a/mozilla/content/base/public/nsIXMLHttpRequest.idl
+++ b/mozilla/content/base/public/nsIXMLHttpRequest.idl
@@ -90,7 +90,7 @@ interface nsPIDOMWindow;
  * you're aware of all the security implications.  And then think twice about
  * it.
  */
-[scriptable, uuid(f3fb86e6-5914-4b47-a1f6-8907e37e1159)]
+[scriptable, uuid(acda85ab-d06c-4176-b834-6d129ca97ca3)]
 interface nsIXMLHttpRequest : nsISupports
 {
   /**
@@ -301,6 +301,15 @@ interface nsIXMLHttpRequest : nsISupports
    */
   attribute boolean multipart;
 
+  /**
+   * Set to true if this is a background service request. This will
+   * prevent a load group being associated with the request, and
+   * suppress any security dialogs from being shown * to the user.
+   * In the cases where one of those dialogs would be shown, the request
+   * will simply fail instead.
+   */
+  attribute boolean mozBackgroundRequest;
+
   /**
    * Initialize the object for use from C++ code with the principal, script
    * context, and owner window that should be used.
diff --git a/mozilla/content/base/src/Makefile.in b/mozilla/content/base/src/Makefile.in
index 0ea3c0fd47d..43a5dab7345 100644
--- a/mozilla/content/base/src/Makefile.in
+++ b/mozilla/content/base/src/Makefile.in
@@ -174,6 +174,8 @@ GQI_SRCS = contentbase.gqi
 # static lib.
 FORCE_STATIC_LIB = 1
 
+EXTRA_COMPONENTS = $(srcdir)/nsBadCertHandler.js
+
 include $(topsrcdir)/config/rules.mk
 
 INCLUDES	+= \
diff --git a/mozilla/content/base/src/nsBadCertHandler.js b/mozilla/content/base/src/nsBadCertHandler.js
new file mode 100644
index 00000000000..b475bce9c82
--- /dev/null
+++ b/mozilla/content/base/src/nsBadCertHandler.js
@@ -0,0 +1,83 @@
+/* ***** 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 the Update Service.
+ *
+ * The Initial Developer of the Original Code is Ben Goodger.
+ * Portions created by the Initial Developer are Copyright (C) 2004
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *  Darin Fisher <darin@meer.net>
+ *  Daniel Veditz <dveditz@mozilla.com>
+ *  Manish Singh <manish@flock.com>
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either 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 ***** */
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+const Cr = Components.results;
+const Cu = Components.utils;
+
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+
+/**
+ * This component's job is to prevent "bad cert" security dialogs from
+ * being shown to the user when in XHR backgroundRequest mode. This
+ * causes the request to simply fail if the certificate is bad.
+ */
+function BadCertHandler() {
+}
+
+BadCertHandler.prototype = {
+
+  // Suppress any certificate errors
+  notifyCertProblem: function(socketInfo, status, targetSite) {
+    return true;
+  },
+
+  // Suppress any ssl errors
+  notifySSLError: function(socketInfo, error, targetSite) {
+    return true;
+  },
+
+  // nsIInterfaceRequestor
+  getInterface: function(iid) {
+    return this.QueryInterface(iid);
+  },
+
+  // nsISupports
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsIBadCertListener2,
+                                         Ci.nsISSLErrorListener,
+                                         Ci.nsIInterfaceRequestor]),
+
+  classDescription: "XMLHttpRequest Bad Cert Handler",
+  classID:          Components.ID("{dbded6ec-edbf-4054-a834-287b82c260f9}"),
+  contractID:       "@mozilla.org/content/xmlhttprequest-bad-cert-handler;1"
+};
+
+function NSGetModule(aCompMgr, aFileSpec) {
+  return XPCOMUtils.generateModule([BadCertHandler]);
+}
diff --git a/mozilla/content/base/src/nsXMLHttpRequest.cpp b/mozilla/content/base/src/nsXMLHttpRequest.cpp
index e3225a7d88b..b84f05ba4c6 100644
--- a/mozilla/content/base/src/nsXMLHttpRequest.cpp
+++ b/mozilla/content/base/src/nsXMLHttpRequest.cpp
@@ -119,6 +119,7 @@
 #define XML_HTTP_REQUEST_USE_XSITE_AC   (1 << 13) // Internal
 #define XML_HTTP_REQUEST_NON_GET        (1 << 14) // Internal
 #define XML_HTTP_REQUEST_GOT_FINAL_STOP (1 << 15) // Internal
+#define XML_HTTP_REQUEST_BACKGROUND     (1 << 16) // Internal
 
 #define XML_HTTP_REQUEST_LOADSTATES         \
   (XML_HTTP_REQUEST_UNINITIALIZED |         \
@@ -131,6 +132,9 @@
 
 #define ACCESS_CONTROL_CACHE_SIZE 100
 
+#define NS_BADCERTHANDLER_CONTRACTID \
+  "@mozilla.org/content/xmlhttprequest-bad-cert-handler;1"
+
 // This helper function adds the given load flags to the request's existing
 // load flags.
 static void AddLoadFlags(nsIRequest *request, nsLoadFlags newFlags)
@@ -141,6 +145,15 @@ static void AddLoadFlags(nsIRequest *request, nsLoadFlags newFlags)
   request->SetLoadFlags(flags);
 }
 
+static nsresult IsCapabilityEnabled(const char *capability, PRBool *enabled)
+{
+  nsIScriptSecurityManager *secMan = nsContentUtils::GetSecurityManager();
+  if (!secMan)
+    return NS_ERROR_FAILURE;
+
+  return secMan->IsCapabilityEnabled(capability, enabled);
+}
+
 // Helper proxy class to be used when expecting an
 // multipart/x-mixed-replace stream of XML documents.
 
@@ -1224,6 +1237,10 @@ nsXMLHttpRequest::GetLoadGroup(nsILoadGroup **aLoadGroup)
   NS_ENSURE_ARG_POINTER(aLoadGroup);
   *aLoadGroup = nsnull;
 
+  if (mState & XML_HTTP_REQUEST_BACKGROUND) {
+    return NS_OK;
+  }
+
   nsCOMPtr<nsIDocument> doc = GetDocumentFromScriptContext(mScriptContext);
   if (doc) {
     *aLoadGroup = doc->GetDocumentLoadGroup().get();  // already_AddRefed
@@ -2391,13 +2408,8 @@ nsXMLHttpRequest::SetRequestHeader(const nsACString& header,
   // Prevent modification to certain HTTP headers (see bug 302263), unless
   // the executing script has UniversalBrowserWrite permission.
 
-  nsIScriptSecurityManager *secMan = nsContentUtils::GetSecurityManager();
-  if (!secMan) {
-    return NS_ERROR_FAILURE;
-  }
-
   PRBool privileged;
-  rv = secMan->IsCapabilityEnabled("UniversalBrowserWrite", &privileged);
+  rv = IsCapabilityEnabled("UniversalBrowserWrite", &privileged);
   if (NS_FAILED(rv))
     return NS_ERROR_FAILURE;
 
@@ -2508,6 +2520,41 @@ nsXMLHttpRequest::SetMultipart(PRBool aMultipart)
   return NS_OK;
 }
 
+/* attribute boolean mozBackgroundRequest; */
+NS_IMETHODIMP
+nsXMLHttpRequest::GetMozBackgroundRequest(PRBool *_retval)
+{
+  *_retval = !!(mState & XML_HTTP_REQUEST_BACKGROUND);
+
+  return NS_OK;
+}
+
+/* attribute boolean mozBackgroundRequest; */
+NS_IMETHODIMP
+nsXMLHttpRequest::SetMozBackgroundRequest(PRBool aMozBackgroundRequest)
+{
+  PRBool privileged;
+
+  nsresult rv = IsCapabilityEnabled("UniversalXPConnect", &privileged);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (!privileged)
+    return NS_ERROR_DOM_SECURITY_ERR;
+
+  if (!(mState & XML_HTTP_REQUEST_UNINITIALIZED)) {
+    // Can't change this while we're in the middle of something.
+    return NS_ERROR_IN_PROGRESS;
+  }
+
+  if (aMozBackgroundRequest) {
+    mState |= XML_HTTP_REQUEST_BACKGROUND;
+  } else {
+    mState &= ~XML_HTTP_REQUEST_BACKGROUND;
+  }
+
+  return NS_OK;
+}
+
 
 // nsIDOMEventListener
 nsresult
@@ -2748,6 +2795,19 @@ nsXMLHttpRequest::GetInterface(const nsIID & aIID, void **aResult)
     }
   }
 
+  if (mState & XML_HTTP_REQUEST_BACKGROUND) {
+    nsresult rv;
+    nsCOMPtr<nsIInterfaceRequestor> badCertHandler(do_CreateInstance(NS_BADCERTHANDLER_CONTRACTID, &rv));
+
+    // Ignore failure to get component, we may not have all its dependencies
+    // available
+    if (NS_SUCCEEDED(rv)) {
+      rv = badCertHandler->GetInterface(aIID, aResult);
+      if (NS_SUCCEEDED(rv))
+        return rv;
+    }
+  }
+
   return QueryInterface(aIID, aResult);
 }
 
diff --git a/mozilla/content/base/test/Makefile.in b/mozilla/content/base/test/Makefile.in
index 7350d7bb086..4b9225a1b1e 100644
--- a/mozilla/content/base/test/Makefile.in
+++ b/mozilla/content/base/test/Makefile.in
@@ -120,6 +120,7 @@ _TEST_FILES = 	test_bug5141.html \
 		test_bug375314.html \
 		test_bug378969.html \
 		test_bug382113.html \
+		test_bug383430.html \
 		test_bug390219.html \
 		test_bug390735.html \
 		test_bug392318.html \
diff --git a/mozilla/content/base/test/test_bug383430.html b/mozilla/content/base/test/test_bug383430.html
new file mode 100644
index 00000000000..ba150e0f84b
--- /dev/null
+++ b/mozilla/content/base/test/test_bug383430.html
@@ -0,0 +1,33 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=383430
+-->
+<head>
+  <title>Test for Bug 383430</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>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=383430">Mozilla Bug 383430</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+  
+</div>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+/** Test for Bug 383430 **/
+netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
+
+var req = new XMLHttpRequest();
+req.mozBackgroundRequest = true;
+req.open("GET", window.location.href);
+req.send(null);
+
+ok(req.channel.loadGroup == null, "loadGroup is null");
+</script>
+</pre>
+</body>
+</html>