IPC: Make ChannelReader inherit from SupportsAttachmentBrokering.

ipc/ipc_channel_proxy.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_PROXY_H_
 #define IPC_IPC_CHANNEL_PROXY_H_
 
 #include <vector>
 
 #include "base/memory/ref_counted.h"
@@ skipping 64 matching lines @@
 #endif
 
   // Initializes a channel proxy.  The channel_handle and mode parameters are
   // passed directly to the underlying IPC::Channel.  The listener is called on
   // the thread that creates the ChannelProxy.  The filter's OnMessageReceived
   // method is called on the thread where the IPC::Channel is running.  The
   // filter may be null if the consumer is not interested in handling messages
   // on the background thread.  Any message not handled by the filter will be
   // dispatched to the listener.  The given task runner correspond to a thread
   // on which IPC::Channel is created and used (e.g. IO thread).
+  // 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<ChannelProxy> Create(
       const IPC::ChannelHandle& channel_handle,
       Channel::Mode mode,
       Listener* listener,
-      const scoped_refptr<base::SingleThreadTaskRunner>& ipc_task_runner);
+      const scoped_refptr<base::SingleThreadTaskRunner>& ipc_task_runner,
+      AttachmentBroker* broker = nullptr);
 
   static scoped_ptr<ChannelProxy> Create(
       scoped_ptr<ChannelFactory> factory,
       Listener* listener,
       const scoped_refptr<base::SingleThreadTaskRunner>& ipc_task_runner);
 
   ~ChannelProxy() override;
 
   // Initializes the channel proxy. Only call this once to initialize a channel
   // proxy that was not initialized in its constructor. If create_pipe_now is
   // true, the pipe is created synchronously. Otherwise it's created on the IO
   // thread.
-  void Init(const IPC::ChannelHandle& channel_handle, Channel::Mode mode,
-            bool create_pipe_now);
+  // TODO(erikchen): Remove default parameter for |broker|. It exists only to
+  // make the upcoming refactor decomposable into smaller CLs.
+  // http://crbug.com/493414.
+  void Init(const IPC::ChannelHandle& channel_handle,
+            Channel::Mode mode,
+            bool create_pipe_now,
+            AttachmentBroker* broker = nullptr);
   void Init(scoped_ptr<ChannelFactory> factory, bool create_pipe_now);
 
   // Close the IPC::Channel.  This operation completes asynchronously, once the
   // background thread processes the command to close the channel.  It is ok to
   // call this method multiple times.  Redundant calls are ignored.
   //
   // WARNING: MessageFilter objects held by the ChannelProxy is also
   // released asynchronously, and it may in fact have its final reference
   // released on the background thread.  The caller should be careful to deal
   // with / allow for this possibility.
@@ skipping 173 matching lines @@
   bool did_init_;
 
 #if defined(ENABLE_IPC_FUZZER)
   OutgoingMessageFilter* outgoing_message_filter_;
 #endif
 };
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_CHANNEL_PROXY_H_