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

content/browser/renderer_host/render_view_host_impl.cc

Index: content/browser/renderer_host/render_view_host_impl.cc
===================================================================
--- content/browser/renderer_host/render_view_host_impl.cc	(revision 271040)
+++ content/browser/renderer_host/render_view_host_impl.cc	(working copy)
@@ -969,8 +969,7 @@
     return true;
 
   bool handled = true;
-  bool msg_is_ok = true;
-  IPC_BEGIN_MESSAGE_MAP_EX(RenderViewHostImpl, msg, msg_is_ok)
+  IPC_BEGIN_MESSAGE_MAP(RenderViewHostImpl, msg)
     IPC_MESSAGE_HANDLER(ViewHostMsg_ShowView, OnShowView)
     IPC_MESSAGE_HANDLER(ViewHostMsg_ShowWidget, OnShowWidget)
     IPC_MESSAGE_HANDLER(ViewHostMsg_ShowFullscreenWidget,
@@ -1023,15 +1022,8 @@
     // Have the super handle all other messages.
     IPC_MESSAGE_UNHANDLED(
         handled = RenderWidgetHostImpl::OnMessageReceived(msg))
-  IPC_END_MESSAGE_MAP_EX()
+  IPC_END_MESSAGE_MAP()
 
-  if (!msg_is_ok) {
-    // The message had a handler, but its de-serialization failed.
-    // Kill the renderer.
-    RecordAction(base::UserMetricsAction("BadMessageTerminate_RVH"));
-    GetProcess()->ReceivedBadMessage();
-  }
-
   return handled;
 }