Add interfaces for most major Blimp net components.

blimp/net/blimp_message_buffer.h

Index: blimp/net/blimp_message_buffer.h
diff --git a/blimp/net/blimp_message_buffer.h b/blimp/net/blimp_message_buffer.h
new file mode 100644
index 0000000000000000000000000000000000000000..a6389bbc68b5416ffb365e4fee3b097ec50ea43b
--- /dev/null
+++ b/blimp/net/blimp_message_buffer.h
@@ -0,0 +1,51 @@
+// Copyright 2015 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 BLIMP_NET_BLIMP_MESSAGE_BUFFER_H_
+#define BLIMP_NET_BLIMP_MESSAGE_BUFFER_H_
+
+#include "base/macros.h"
+#include "blimp/net/blimp_message_ack_observer.h"
+#include "blimp/net/blimp_message_processor.h"
+
+namespace blimp {
+
+class BlimpConnection;
+
+// Provides a reliable, ordered outgoing message buffer.

[haibinlu, 2015/11/04 00:41:26]

"reliable message buffer" ? or, this buffer is just part of reliable, ordered
blimp message delivery mechanism. 

[Kevin M, 2015/11/04 20:09:02]

Done.

+// Messages are available for redelivery until they are acknowledged by the
+//    receiving end (via BlimpMessageAckObserver).
+class BlimpMessageBuffer : public BlimpMessageProcessor,

[haibinlu, 2015/11/04 00:41:26]

BlimpOutgoingMessageBuffer? so it is clear that this is not incoming message
buffer. 

[Kevin M, 2015/11/04 20:09:01]

That might be chopping up the terms a bit too much. How about this:
"BlimpMessageOutputBuffer", an output buffer for BlimpMessages.

[haibinlu, 2015/11/04 20:33:20]

BlimpMessageOutputBuffer sgtm.

+                           public BlimpMessageAckObserver {
+ public:
+  BlimpMessageBuffer();
+
+  ~BlimpMessageBuffer() override;
+
+  // Sets the processor for receiving messages from this buffer.
+  void SetOutgoingMessageProcessor(scoped_ptr<BlimpMessageProcessor> processor);
+
+  // BlimpMessageProcessor implementation.
+  // |callback|, if set, will be called once the remote end has acknowledged the
+  //     receipt of |message|.
+  // A sequence of N dependent writes with one acknowledgement can be had by
+  //     calling ProcessMessage() N-1 times with an empty |callback|, then
+  //     calling the final (Nth) message with |callback| set.
+  void ProcessMessage(const BlimpMessage& message,

[haibinlu, 2015/11/04 00:41:26]

private ?

[Kevin M, 2015/11/04 20:09:01]

I think this should be public, because this is the public interface that's
invoked from other classes and tests. They're not implementation details that we
need to encapsulate.

+                      const net::CompletionCallback& callback) override;
+
+  // MessageAckObserver implementation.
+  // Removes BlimpMessages from the buffer whose ID is less than or equal to
+  // |message_id|.
+  // Invokes outstanding CompletionCallbacks for previously unacknowledged
+  // messages which have an ID less than or equal to |message_id|.
+  void OnMessageAck(int64 message_id) override;

[haibinlu, 2015/11/04 00:41:26]

private?

[Kevin M, 2015/11/04 20:09:02]

Ditto

+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(BlimpMessageBuffer);
+};
+
+}  // namespace blimp
+
+#endif  // BLIMP_NET_BLIMP_MESSAGE_BUFFER_H_