Remove obviously unneeded forward declarations in chrome/browser/[abef]*/*.h.

chrome/browser/extensions/sandboxed_extension_unpacker.h

Index: chrome/browser/extensions/sandboxed_extension_unpacker.h
diff --git a/chrome/browser/extensions/sandboxed_extension_unpacker.h b/chrome/browser/extensions/sandboxed_extension_unpacker.h
index 932bb5d606dcd0643399bca60dc0e94ea8b197b2..a9b6408f5f810c860963c132b62c2d6a828f0d6f 100644
--- a/chrome/browser/extensions/sandboxed_extension_unpacker.h
+++ b/chrome/browser/extensions/sandboxed_extension_unpacker.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -15,7 +15,6 @@
 #include "chrome/browser/utility_process_host.h"
 
 class Extension;
-class MessageLoop;
 class ResourceDispatcherHost;
 
 class SandboxedExtensionUnpackerClient