ipc: Make a new class PlaceholderBrokerableAttachment.

ipc/handle_attachment_win.cc

Index: ipc/handle_attachment_win.cc
diff --git a/ipc/handle_attachment_win.cc b/ipc/handle_attachment_win.cc
index 50e3e6dab24310c5bba54d5f44cfa42cb436630e..b7f43734b5bc7500af56629432ed5ae3da547aec 100644
--- a/ipc/handle_attachment_win.cc
+++ b/ipc/handle_attachment_win.cc
@@ -14,13 +14,13 @@ HandleAttachmentWin::HandleAttachmentWin(const HANDLE& handle,
     : handle_(handle), permissions_(permissions) {}
 
 HandleAttachmentWin::HandleAttachmentWin(const WireFormat& wire_format)
-    : BrokerableAttachment(wire_format.attachment_id, false),
+    : BrokerableAttachment(wire_format.attachment_id),
       handle_(LongToHandle(wire_format.handle)),
       permissions_(wire_format.permissions) {}
 
 HandleAttachmentWin::HandleAttachmentWin(
     const BrokerableAttachment::AttachmentId& id)
-    : BrokerableAttachment(id, true),
+    : BrokerableAttachment(id),
       handle_(INVALID_HANDLE_VALUE),
       permissions_(HandleWin::INVALID) {}
 
@@ -32,19 +32,6 @@ HandleAttachmentWin::BrokerableType HandleAttachmentWin::GetBrokerableType()
   return WIN_HANDLE;
 }
 
-void HandleAttachmentWin::PopulateWithAttachment(
-    const BrokerableAttachment* attachment) {
-  DCHECK(NeedsBrokering());
-  DCHECK(!attachment->NeedsBrokering());
-  DCHECK(GetIdentifier() == attachment->GetIdentifier());
-  DCHECK_EQ(GetBrokerableType(), attachment->GetBrokerableType());
-
-  const HandleAttachmentWin* handle_attachment =
-      static_cast<const HandleAttachmentWin*>(attachment);
-  handle_ = handle_attachment->handle_;
-  SetNeedsBrokering(false);
-}
-
 HandleAttachmentWin::WireFormat HandleAttachmentWin::GetWireFormat(
     const base::ProcessId& destination) const {
   WireFormat format;