Reland #1: Clean up interface of attachment broker.

ipc/ipc_channel.h

 // Copyright (c) 2012 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_IPC_CHANNEL_H_
 #define IPC_IPC_CHANNEL_H_
 
 #include <string>
 
 #if defined(OS_POSIX)
@@ skipping 147 matching lines @@
       AttachmentBroker* broker);
 #endif
   // TODO(erikchen): Remove default parameter for |broker|. It exists only to
   // make the upcoming refactor decomposable into smaller CLs.
   // http://crbug.com/493414.
   static scoped_ptr<Channel> CreateServer(
       const IPC::ChannelHandle& channel_handle,
       Listener* listener,
       AttachmentBroker* broker = nullptr);
 
+  Channel() : attachment_broker_endpoint_(false) {}
   ~Channel() override;
 
   // Connect the pipe.  On the server side, this will initiate
   // waiting for connections.  On the client, it attempts to
   // connect to a pre-existing pipe.  Note, calling Connect()
   // will not block the calling thread and may complete
   // asynchronously.
   virtual bool Connect() WARN_UNUSED_RESULT = 0;
 
   // Close this Channel explicitly.  May be called multiple times.
@@ skipping 67 matching lines @@
 #endif
 
 #if defined(OS_ANDROID)
   // Most tests are single process and work the same on all platforms. However
   // in some cases we want to test multi-process, and Android differs in that it
   // can't 'exec' after forking. This callback resets any data in the forked
   // process such that it acts similar to if it was exec'd, for tests.
   static void NotifyProcessForkedForTesting();
 #endif
 
+  void set_attachment_broker_endpoint(bool is_endpoint) {
+    attachment_broker_endpoint_ = is_endpoint;
+  }
+
+ protected:
+  bool is_attachment_broker_endpoint() { return attachment_broker_endpoint_; }
+
+ private:
+  // Whether this channel is used as an endpoint for sending and receiving
+  // brokerable attachment messages to/from the broker process.
+  bool attachment_broker_endpoint_;
 };
 
 #if defined(OS_POSIX)
 // SocketPair() creates a pair of socket FDs suitable for using with
 // IPC::Channel.
 IPC_EXPORT bool SocketPair(int* fd1, int* fd2);
 #endif
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_CHANNEL_H_