Revert of Remove IPC::BrokerableAttachment.

ipc/ipc_channel_mojo_unittest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ipc/ipc_channel_mojo.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <memory>
@@ skipping 271 matching lines @@
     WriteFile(message, file);
     WritePipe(message, pipe);
     ASSERT_TRUE(sender->Send(message));
   }
 
   static void ReadReceivedFile(const IPC::Message& message,
                                base::PickleIterator* iter) {
     base::ScopedFD fd;
     scoped_refptr<base::Pickle::Attachment> attachment;
     EXPECT_TRUE(message.ReadAttachment(iter, &attachment));
-    EXPECT_EQ(
-        IPC::MessageAttachment::Type::PLATFORM_FILE,
-        static_cast<IPC::MessageAttachment*>(attachment.get())->GetType());
-    base::File file(
-        static_cast<IPC::internal::PlatformFileAttachment*>(attachment.get())
-            ->TakePlatformFile());
+    EXPECT_EQ(IPC::MessageAttachment::TYPE_PLATFORM_FILE,
+              static_cast<IPC::MessageAttachment*>(attachment.get())
+                  ->GetType());
+    base::File file(static_cast<IPC::MessageAttachment*>(attachment.get())
+                        ->TakePlatformFile());
     std::string content(GetSendingFileContent().size(), ' ');
     file.Read(0, &content[0], content.size());
     EXPECT_EQ(content, GetSendingFileContent());
   }
 #endif
 };
 
 class ListenerThatExpectsMessagePipe : public IPC::Listener {
  public:
   ListenerThatExpectsMessagePipe() : sender_(NULL) {}
@@ skipping 1102 matching lines @@
   Connect(&listener);
 
   base::RunLoop().Run();
 
   Close();
 }
 
 #endif  // OS_LINUX
 
 }  // namespace