Revert of Remove IPC::BrokerableAttachment.

ipc/ipc_channel_reader_unittest.cc

Index: ipc/ipc_channel_reader_unittest.cc
diff --git a/ipc/ipc_channel_reader_unittest.cc b/ipc/ipc_channel_reader_unittest.cc
index a3d80dc922e7631e1bdf2eb1a256f6c01494dd64..16c6649c3a1f166627d393e42f83a632b5c52524 100644
--- a/ipc/ipc_channel_reader_unittest.cc
+++ b/ipc/ipc_channel_reader_unittest.cc
@@ -12,6 +12,7 @@
 #include <set>
 
 #include "base/run_loop.h"
+#include "ipc/brokerable_attachment.h"
 #include "ipc/ipc_channel_reader.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -38,7 +39,7 @@
 
   bool ShouldDispatchInputMessage(Message* msg) override { return true; }
 
-  bool GetAttachments(Message* msg) override { return true; }
+  bool GetNonBrokeredAttachments(Message* msg) override { return true; }
 
   bool DidEmptyInputBuffers() override { return true; }