Remove obsolete methods from IPC::Channel and related classes.

ipc/ipc_channel_proxy.h

Index: ipc/ipc_channel_proxy.h
diff --git a/ipc/ipc_channel_proxy.h b/ipc/ipc_channel_proxy.h
index c90a4c639ba8352836658d93c64c275c177b915d..d54f3e9725a063a92f543b228c947e940fedb176 100644
--- a/ipc/ipc_channel_proxy.h
+++ b/ipc/ipc_channel_proxy.h
@@ -238,12 +238,6 @@ class IPC_EXPORT ChannelProxy : public Endpoint, public base::NonThreadSafe {
   base::ProcessId GetPeerPID() const override;
   void OnSetAttachmentBrokerEndpoint() override;
 
-#if defined(OS_POSIX) && !defined(OS_NACL_SFI)
-  // Calls through to the underlying channel's methods.
-  int GetClientFileDescriptor();
-  base::ScopedFD TakeClientFileDescriptor();
-#endif
-
  protected:
   class Context;
   // A subclass uses this constructor if it needs to add more information