Refactoring: Move MessagePipeReader subclasess out from ChannelMojo

ipc/mojo/ipc_channel_mojo.h

Index: ipc/mojo/ipc_channel_mojo.h
diff --git a/ipc/mojo/ipc_channel_mojo.h b/ipc/mojo/ipc_channel_mojo.h
index dd57bc8bf9aa45d3ed57581cc0fc2ab19d1e2e26..22c56a9e6894643e51f6f3838131dc6da513c8ce 100644
--- a/ipc/mojo/ipc_channel_mojo.h
+++ b/ipc/mojo/ipc_channel_mojo.h
@@ -24,6 +24,13 @@ struct ChannelInfo;
 
 namespace IPC {
 
+namespace internal {
+class ControlReader;
+class ServerControlReader;
+class ClientControlReader;
+class MessageReader;
+}
+
 // Mojo-based IPC::Channel implementation over a platform handle.
 //
 // ChannelMojo builds Mojo MessagePipe using underlying pipe given by
@@ -74,6 +81,15 @@ class IPC_MOJO_EXPORT ChannelMojo : public Channel {
 #if defined(OS_POSIX) && !defined(OS_NACL)
   virtual int GetClientFileDescriptor() const OVERRIDE;
   virtual int TakeClientFileDescriptor() OVERRIDE;
+
+  // These access protected API of IPC::Message, which has ChannelMojo
+  // as a friend class.
+  static MojoResult WriteToFileDescriptorSet(
+      const std::vector<MojoHandle>& handle_buffer,
+      Message* message);
+  static MojoResult ReadFromFileDescriptorSet(const Message& message,
+                                              std::vector<MojoHandle>* handles);
+
 #endif  // defined(OS_POSIX) && !defined(OS_NACL)
 
   // Called from MessagePipeReader implementations
@@ -83,6 +99,12 @@ class IPC_MOJO_EXPORT ChannelMojo : public Channel {
   void OnPipeError(internal::MessagePipeReader* reader);
   void set_peer_pid(base::ProcessId pid) { peer_pid_ = pid; }
 
+ protected:
+  ChannelMojo(const ChannelHandle& channel_handle,
+              Mode mode,
+              Listener* listener,
+              scoped_refptr<base::TaskRunner> io_thread_task_runner);
+
  private:
   struct ChannelInfoDeleter {
     void operator()(mojo::embedder::ChannelInfo* ptr) const;
@@ -93,14 +115,6 @@ class IPC_MOJO_EXPORT ChannelMojo : public Channel {
   // notifications invoked by them.
   typedef internal::MessagePipeReader::DelayedDeleter ReaderDeleter;
 
-  class ControlReader;
-  class ServerControlReader;
-  class ClientControlReader;
-  class MessageReader;
-
-  ChannelMojo(scoped_ptr<Channel> bootstrap, Mode mode, Listener* listener,
-              scoped_refptr<base::TaskRunner> io_thread_task_runner);
-
   void InitOnIOThread();
 
   scoped_ptr<Channel> bootstrap_;
@@ -110,8 +124,8 @@ class IPC_MOJO_EXPORT ChannelMojo : public Channel {
   scoped_ptr<mojo::embedder::ChannelInfo,
              ChannelInfoDeleter> channel_info_;
 
-  scoped_ptr<ControlReader, ReaderDeleter> control_reader_;
-  scoped_ptr<MessageReader, ReaderDeleter> message_reader_;
+  scoped_ptr<internal::ControlReader, ReaderDeleter> control_reader_;
+  scoped_ptr<internal::MessageReader, ReaderDeleter> message_reader_;
   ScopedVector<Message> pending_messages_;
 
   base::WeakPtrFactory<ChannelMojo> weak_factory_;