Remove IPC_BEGIN_MESSAGE_MAP_EX macro since r270839 made all bad IPCs kill their child processes.

chrome/browser/printing/printing_message_filter.cc

Index: chrome/browser/printing/printing_message_filter.cc
===================================================================
--- chrome/browser/printing/printing_message_filter.cc	(revision 271040)
+++ chrome/browser/printing/printing_message_filter.cc	(working copy)
@@ -115,10 +115,9 @@
 #endif
 }
 
-bool PrintingMessageFilter::OnMessageReceived(const IPC::Message& message,
-                                              bool* message_was_ok) {
+bool PrintingMessageFilter::OnMessageReceived(const IPC::Message& message) {
   bool handled = true;
-  IPC_BEGIN_MESSAGE_MAP_EX(PrintingMessageFilter, message, *message_was_ok)
+  IPC_BEGIN_MESSAGE_MAP(PrintingMessageFilter, message)
 #if defined(OS_WIN)
     IPC_MESSAGE_HANDLER(PrintHostMsg_DuplicateSection, OnDuplicateSection)
 #endif