Update ChannelReader to use AttachmentBroker.

ipc/attachment_broker_win.h

 // Copyright 2015 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.
 
 #ifndef IPC_ATTACHMENT_BROKER_WIN_H_
 #define IPC_ATTACHMENT_BROKER_WIN_H_
 
 #include <vector>
 
 #include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted.h"
 #include "ipc/attachment_broker.h"
+#include "ipc/brokerable_attachment.h"
 #include "ipc/handle_attachment_win.h"
 #include "ipc/ipc_export.h"
 
 namespace IPC {
 
 class Sender;
 
 // This class is an implementation of AttachmentBroker for the Windows platform.
 class IPC_EXPORT AttachmentBrokerWin : public IPC::AttachmentBroker {
  public:
   AttachmentBrokerWin();
   ~AttachmentBrokerWin() override;
 
   // In a non-broker process, the single instance of this class listens for
   // an IPC from the broker process indicating that a new attachment has been
   // duplicated.
   void OnReceiveDuplicatedHandle(HANDLE, BrokerableAttachment::AttachmentId id);
 
   // IPC::AttachmentBroker overrides.
   bool SendAttachmentToProcess(const BrokerableAttachment* attachment,
                                base::ProcessId destination_process) override;
-  bool GetAttachmentWithId(BrokerableAttachment::AttachmentId id,
-                           BrokerableAttachment* attachment) override;
+  bool GetAttachmentWithId(
+      BrokerableAttachment::AttachmentId id,
+      scoped_refptr<BrokerableAttachment>* attachment) override;
 
   // IPC::Listener overrides.
   bool OnMessageReceived(const Message& message) override;
 
   // |sender_| is used to send Messages to the broker. |sender_| must live at
   // least as long as this instance.
   void set_sender(IPC::Sender* sender) { sender_ = sender; }
 
  private:
   FRIEND_TEST_ALL_PREFIXES(AttachmentBrokerWinTest, ReceiveValidMessage);
   FRIEND_TEST_ALL_PREFIXES(AttachmentBrokerWinTest, ReceiveInvalidMessage);
+  using AttachmentVector = std::vector<scoped_refptr<BrokerableAttachment>>;
 
   // IPC message handlers.
   void OnWinHandleHasBeenDuplicated(
       const IPC::internal::HandleAttachmentWin::WireFormat& wire_format);
 
   // A vector of BrokerableAttachments that have been received, but not yet
   // consumed.
   // A std::vector is used instead of a std::map because this container is
   // expected to have few elements, for which a std::vector is expected to have
   // better performance.
-  std::vector<scoped_refptr<BrokerableAttachment>> attachments_;
+  AttachmentVector attachments_;
 
   // |sender_| is used to send Messages to the broker. |sender_| must live at
   // least as long as this instance.
   IPC::Sender* sender_;
   DISALLOW_COPY_AND_ASSIGN(AttachmentBrokerWin);
 };
 
 }  // namespace IPC
 
 #endif  // IPC_ATTACHMENT_BROKER_WIN_H_