Mojo: First stab at making MessagePipes work across OS pipes.

mojo/system/raw_channel.h

 // Copyright 2013 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 MOJO_SYSTEM_RAW_CHANNEL_H_
 #define MOJO_SYSTEM_RAW_CHANNEL_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 28 matching lines @@
 // |Create()| static factory method.
 //
 // With the exception of |WriteMessage()|, this class is thread-unsafe (and in
 // general its methods should only be used on the I/O thread).
 class MOJO_SYSTEM_EXPORT RawChannel {
  public:
   virtual ~RawChannel() {}
 
   // The |Delegate| is only accessed on the same thread as the message loop
   // (passed in on creation).
-  class Delegate {
+  class MOJO_SYSTEM_EXPORT Delegate {
    public:
     enum FatalError {
       FATAL_ERROR_UNKNOWN = 0,
       FATAL_ERROR_FAILED_READ,
       FATAL_ERROR_FAILED_WRITE
     };
 
     // Called when a message is read. This may call |Shutdown()| on the
     // |RawChannel|, but must not destroy it.
     virtual void OnReadMessage(const MessageInTransit& message) = 0;
 
     // Called when there's a fatal error, which leads to the channel no longer
     // being viable.
     virtual void OnFatalError(FatalError fatal_error) = 0;
 
    protected:
     virtual ~Delegate() {}
   };
 
   // Static factory method. Takes ownership of |handle| (i.e., will close it).
   // Does *not* take ownership of |delegate| and |message_loop|, which must
   // remain alive while this object does.
   static RawChannel* Create(const PlatformChannelHandle& handle,
                             Delegate* delegate,
                             base::MessageLoop* message_loop);
 
-  // This must be called (on the I/O thread) before this object is used.
-  virtual void Init() = 0;
+  // This must be called (on the I/O thread) before this object is used. Returns
+  // true on success. On failure, |Shutdown()| should *not* be called.
+  virtual bool Init() = 0;
 
   // This must be called (on the I/O thread) before this object is destroyed.
   virtual void Shutdown() = 0;
 
   // This is thread-safe. It takes ownership of |message| (always, even on
   // failure). Returns true on success.
   virtual bool WriteMessage(MessageInTransit* message) = 0;
 
  protected:
   RawChannel(Delegate* delegate, base::MessageLoop* message_loop)
       : delegate_(delegate), message_loop_(message_loop) {}
 
   Delegate* delegate() { return delegate_; }
   base::MessageLoop* message_loop() { return message_loop_; }
 
  private:
   Delegate* const delegate_;
   base::MessageLoop* const message_loop_;
 
   DISALLOW_COPY_AND_ASSIGN(RawChannel);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_RAW_CHANNEL_H_