Add interfaces for most major Blimp net components.

blimp/net/blimp_message_processor.h

Index: blimp/net/blimp_message_processor.h
diff --git a/blimp/net/blimp_message_processor.h b/blimp/net/blimp_message_processor.h
new file mode 100644
index 0000000000000000000000000000000000000000..2ab43c47016771861403dbdc9d8c06fd53ec05a3
--- /dev/null
+++ b/blimp/net/blimp_message_processor.h
@@ -0,0 +1,27 @@
+// 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_PROCESSOR_H_
+#define BLIMP_NET_BLIMP_MESSAGE_PROCESSOR_H_
+
+#include "net/base/completion_callback.h"
+
+namespace blimp {
+
+class BlimpMessage;
+
+// Interface implemented by components that process BlimpMessages.

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

nit: Suggest clarifying that this super-generic interface lets us build
composable message-processing components easily.

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

Done.

+class BlimpMessageProcessor {
+ public:
+  virtual ~BlimpMessageProcessor() {}
+
+  // Processes the BlimpMessage asynchronously.
+  // The result of the operation is returned to the caller via |callback|.
+  virtual void ProcessMessage(const BlimpMessage& message,
+                              const net::CompletionCallback& callback) = 0;
+};
+
+}  // namespace blimp
+
+#endif  // BLIMP_NET_BLIMP_MESSAGE_PROCESSOR_H_