Always leak the Mojo parent pipe handle on child process shutdown.

mojo/edk/system/channel.h

Index: mojo/edk/system/channel.h
diff --git a/mojo/edk/system/channel.h b/mojo/edk/system/channel.h
index f65f41e7b932f11748f0a590e84dacd1cba45e4c..c3fb77bc906185a1547bed64b5249a90700d8bde 100644
--- a/mojo/edk/system/channel.h
+++ b/mojo/edk/system/channel.h
@@ -225,6 +225,10 @@ class Channel : public base::RefCountedThreadSafe<Channel> {
   // Delegate::OnChannelError.
   virtual void Write(MessagePtr message) = 0;
 
+  // Causes the platform handle to leak when this channel is shut down instead
+  // of closing it.
+  virtual void LeakHandle() = 0;
+
  protected:
   explicit Channel(Delegate* delegate);
   virtual ~Channel();