dbus: fix base class of ErrorResponse

dbus::ErrorResponse needs to be a subclass of dbus::Response otherwise
you can't pass it to a dbus::ExportedObject::ResponseSender.

BUG=none
TEST=my code now compiles

Change-Id: I1efba7c2cd9aaed937cac75133ab6b695aeac63b


Review URL: http://codereview.chromium.org/9675002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@126053 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/dbus/message.cc b/dbus/message.cc
index 486538a..43fb3bb 100644
--- a/dbus/message.cc
+++ b/dbus/message.cc
@@ -404,7 +404,7 @@
 // ErrorResponse implementation.
 //
 
-ErrorResponse::ErrorResponse() : Message() {
+ErrorResponse::ErrorResponse() : Response() {
 }
 
 ErrorResponse* ErrorResponse::FromRawMessage(DBusMessage* raw_message) {