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

content/public/test/mock_render_thread.cc

Index: content/public/test/mock_render_thread.cc
===================================================================
--- content/public/test/mock_render_thread.cc	(revision 271040)
+++ content/public/test/mock_render_thread.cc	(working copy)
@@ -238,13 +238,12 @@
   sink_.OnMessageReceived(msg);
 
   bool handled = true;
-  bool msg_is_ok = true;
-  IPC_BEGIN_MESSAGE_MAP_EX(MockRenderThread, msg, msg_is_ok)
+  IPC_BEGIN_MESSAGE_MAP(MockRenderThread, msg)
     IPC_MESSAGE_HANDLER(ViewHostMsg_CreateWidget, OnCreateWidget)
     IPC_MESSAGE_HANDLER(ViewHostMsg_CreateWindow, OnCreateWindow)
     IPC_MESSAGE_HANDLER(FrameHostMsg_CreateChildFrame, OnCreateChildFrame)
     IPC_MESSAGE_UNHANDLED(handled = false)
-  IPC_END_MESSAGE_MAP_EX()
+  IPC_END_MESSAGE_MAP()
   return handled;
 }