Add interfaces for most major Blimp net components.

blimp/net/blimp_message_multiplexer.h

Index: blimp/net/blimp_message_multiplexer.h
diff --git a/blimp/net/blimp_message_multiplexer.h b/blimp/net/blimp_message_multiplexer.h
new file mode 100644
index 0000000000000000000000000000000000000000..5ba0d7cdee554a40cf097fcfbe3361ca711fb613
--- /dev/null
+++ b/blimp/net/blimp_message_multiplexer.h
@@ -0,0 +1,66 @@
+// 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_MULTIPLEXER_H_
+#define BLIMP_NET_BLIMP_MESSAGE_MULTIPLEXER_H_
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "blimp/common/proto/blimp_message.pb.h"
+#include "blimp/net/blimp_message_processor.h"
+#include "blimp/net/blimp_net_export.h"
+#include "net/base/completion_callback.h"
+
+namespace blimp {
+
+class BlimpConnection;
+
+// Creates MessageProcessors that receive outgoing messages and multiplex them

[Wez, 2015/11/12 00:12:54]

nit: Creates->Dispenses?

nit: Suggest dropping "receive outgoing messages and" and instead just  "that
multiplex messages"

[Kevin M, 2015/11/12 01:53:16]

Done.

+// on to a single output message processor.
+class BLIMP_NET_EXPORT BlimpMessageMultiplexer : public BlimpMessageProcessor {

[Wez, 2015/11/12 00:12:54]

This doesn't need to be a BlimpMessageProcessor itself - see comments on that
CL.

(Incidentally, if you have your local branches depending one upon the other then
you won't get the changes from e.g. the BlimpMessageProcessor CL duplicated in
here. You can use that property to break-out bits of this CL, e.g. the
interfaces vs the implementation classes, to land separately, without having to
do to much additional work.)

[Kevin M, 2015/11/12 01:53:16]

Propagated changes across branches.

+ public:
+  // |output_processor|: A pointer to the MessageProcessor that will receive the
+  // multiplexed output of this.

[Wez, 2015/11/12 00:12:54]

nit: multiplexed message stream.

[Kevin M, 2015/11/12 01:53:16]

Done.

+  explicit BlimpMessageMultiplexer(BlimpMessageProcessor* output_processor);
+
+  ~BlimpMessageMultiplexer() override;
+
+  // Creates a BlimpMessageProcessor object for sending messages of type |type|.
+  // Any number of senders can be created at a time for a given type.
+  scoped_ptr<BlimpMessageProcessor> CreateSenderForType(
+      BlimpMessage::Type type);
+
+ private:
+  class MultiplexedSender : public BlimpMessageProcessor {
+   public:
+    MultiplexedSender(BlimpMessageMultiplexer* multiplexer,
+                      BlimpMessage::Type type);
+    ~MultiplexedSender() override;
+
+    // BlimpMessageProcessor implementation.
+    // |message.type| should not be set at the time of calling ProcessMessage.
+    void ProcessMessage(const BlimpMessage& message,
+                        const net::CompletionCallback& callback) override;
+
+   private:
+    BlimpMessageMultiplexer* multiplexer_;
+    BlimpMessage::Type type_;
+
+    DISALLOW_COPY_AND_ASSIGN(MultiplexedSender);
+  };
+  friend class MultiplexedSender;
+
+  // BlimpMessageProcessor implementation.
+  // Private linkage so that only MultiplexedSender may call it.
+  void ProcessMessage(const BlimpMessage& message,
+                      const net::CompletionCallback& callback) override;
+
+  BlimpMessageProcessor* output_processor_;
+
+  DISALLOW_COPY_AND_ASSIGN(BlimpMessageMultiplexer);
+};
+
+}  // namespace blimp
+
+#endif  // BLIMP_NET_BLIMP_MESSAGE_MULTIPLEXER_H_