ipc: Make a common subclass for Channel and ProxyChannel.

ipc/attachment_broker_privileged.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_PRIVILEGED_H_
 #define IPC_ATTACHMENT_BROKER_PRIVILEGED_H_
 
 #include <vector>
 
 #include "ipc/attachment_broker.h"
 #include "ipc/ipc_export.h"
 
 namespace IPC {
 
-class Channel;
+class Endpoint;
+class Sender;
 
 // This abstract subclass of AttachmentBroker is intended for use in a
 // privileged process . When unprivileged processes want to send attachments,
 // the attachments get routed through the privileged process, and more
 // specifically, an instance of this class.
 class IPC_EXPORT AttachmentBrokerPrivileged : public IPC::AttachmentBroker {
  public:
   AttachmentBrokerPrivileged();
   ~AttachmentBrokerPrivileged() override;
 
   // Each unprivileged process should have one IPC channel on which it
   // communicates attachment information with the broker process. In the broker
   // process, these channels must be registered and deregistered with the
   // Attachment Broker as they are created and destroyed.
-  void RegisterCommunicationChannel(Channel* channel);
-  void DeregisterCommunicationChannel(Channel* channel);
+  void RegisterCommunicationChannel(Endpoint* endpoint);
+  void DeregisterCommunicationChannel(Endpoint* endpoint);
 
  protected:
-  // Returns nullptr if no channel is found.
-  Channel* GetChannelWithProcessId(base::ProcessId id);
+  // Returns the sender whose peer's process id is |id|.
+  // Returns nullptr if no sender is found.
+  Sender* GetSenderWithProcessId(base::ProcessId id);
 
  private:
-  std::vector<Channel*> channels_;
+  std::vector<Endpoint*> endpoints_;
   DISALLOW_COPY_AND_ASSIGN(AttachmentBrokerPrivileged);
 };
 
 }  // namespace IPC
 
 #endif  // IPC_ATTACHMENT_BROKER_PRIVILEGED_H_