IPC: Remove unnecessary conversions of BrokerableAttachment.

ipc/attachment_broker_privileged_win_unittest.cc

Index: ipc/attachment_broker_privileged_win_unittest.cc
diff --git a/ipc/attachment_broker_privileged_win_unittest.cc b/ipc/attachment_broker_privileged_win_unittest.cc
index 555262a94a2df4a5fa98fe7f1e9b12c37abfc70a..b0353d6027fe39ec0ec35f7f5891fcabbd11cae4 100644
--- a/ipc/attachment_broker_privileged_win_unittest.cc
+++ b/ipc/attachment_broker_privileged_win_unittest.cc
@@ -276,8 +276,9 @@ class MockBroker : public IPC::AttachmentBrokerUnprivilegedWin {
  public:
   MockBroker() {}
   ~MockBroker() override {}
-  bool SendAttachmentToProcess(IPC::BrokerableAttachment* attachment,
-                               base::ProcessId destination_process) override {
+  bool SendAttachmentToProcess(
+      const scoped_refptr<IPC::BrokerableAttachment>& attachment,
+      base::ProcessId destination_process) override {
     return IPC::AttachmentBrokerUnprivilegedWin::SendAttachmentToProcess(
         attachment, base::Process::Current().Pid());
   }