Separate out IPC::Message::Sender and channel::Listener into a separate class.

ipc/ipc_message.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_MESSAGE_H_
 #define IPC_IPC_MESSAGE_H_
 #pragma once
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/pickle.h"
 #include "ipc/ipc_export.h"
 
+// TODO(brettw) remove this when the "typedef Sender" is removed below.
+#include "ipc/ipc_sender.h"
+
 // Ipc logging adds a dependency from the 'chrome' target on all ipc message
 // classes. In a component build, this would require exporting all message
 // classes, so don't support ipc logging in the components build.
 #if !defined(NDEBUG) && !defined(COMPONENT_BUILD)
 #define IPC_MESSAGE_LOG_ENABLED
 #endif
 
 #if defined(OS_POSIX)
 #include "base/memory/ref_counted.h"
 #endif
 
 namespace base {
 struct FileDescriptor;
 }
 
 class FileDescriptorSet;
 
 namespace IPC {
 
 //------------------------------------------------------------------------------
 
 class Channel;
 class Message;
 struct LogData;
 
 class IPC_EXPORT Message : public Pickle {
  public:
-  // Implemented by objects that can send IPC messages across a channel.
-  class IPC_EXPORT Sender {
-   public:
-    virtual ~Sender() {}
-
-    // Sends the given IPC message.  The implementor takes ownership of the
-    // given Message regardless of whether or not this method succeeds.  This
-    // is done to make this method easier to use.  Returns true on success and
-    // false otherwise.
-    virtual bool Send(Message* msg) = 0;
-  };
+  // IPC::Sender used to be IPC::Message::Sender which prevented forward
+  // declarations. To keep existing code compiling, we provide this backwards-
+  // compatible definition. New code should use IPC::Sender.
+  // TODO(brettw) convert users of this and delete.
+  typedef IPC::Sender Sender;
 
   enum PriorityValue {
     PRIORITY_LOW = 1,
     PRIORITY_NORMAL,
     PRIORITY_HIGH
   };
 
   // Bit values used in the flags field.
   enum {
     PRIORITY_MASK     = 0x0003,  // Low 2 bits of store the priority value.
@@ skipping 219 matching lines @@
   MSG_ROUTING_NONE = -2,
 
   // indicates a general message not sent to a particular tab.
   MSG_ROUTING_CONTROL = kint32max,
 };
 
 #define IPC_REPLY_ID 0xFFFFFFF0  // Special message id for replies
 #define IPC_LOGGING_ID 0xFFFFFFF1  // Special message id for logging
 
 #endif  // IPC_IPC_MESSAGE_H_