Add interfaces for most major Blimp net components.

blimp/net/blimp_connection.h

Index: blimp/net/blimp_connection.h
diff --git a/blimp/net/blimp_connection.h b/blimp/net/blimp_connection.h
index 35336c4f28e8267904a3055c396bdbf2e2a4dd42..e8a086d12ac367f2a721ca659141d1757a922d3e 100644
--- a/blimp/net/blimp_connection.h
+++ b/blimp/net/blimp_connection.h
@@ -6,15 +6,38 @@
 #define BLIMP_NET_BLIMP_CONNECTION_H_
 
 #include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
 #include "blimp/net/blimp_net_export.h"
 
 namespace blimp {
 
+class BlimpMessageProcessor;
+
+// Encapsulates the state and logic used to exchange BlimpMessages over
+// a network connection.
 class BLIMP_NET_EXPORT BlimpConnection {
  public:
+  class DisconnectObserver {
+    // Called when the network connection for |this| is disconnected.
+    virtual void OnDisconnected() = 0;
+  };
+
   BlimpConnection();
+
   ~BlimpConnection();
 
+  // Lets |observer| know when the network connection is terminated.
+  void AddDisconnectObserver(const DisconnectObserver& observer);

[Wez, 2015/11/12 00:12:53]

Strange to have |observer| passed as a const reference - the OnDisconnected()
API on it is not a const method, so how will you call it?

[Kevin M, 2015/11/12 01:53:15]

Good find, it should be a non-const pointer. Done

+
+  // Sets the processor for BlimpConnection->BrowserSession message routing.

[Wez, 2015/11/12 00:12:53]

This class doesn't know anything about BrowserSession directly, so basically
just say that it sets the component to which received messages should be passed.
It _won't_ normally be the BrowserSession, but some sub-component of the
BrowserSession, for example, and this API doesn't care about that detail.

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

Done.

+  // Only one can be set a time. Can be set multiple times, but previously set
+  // incoming message processors are discarded.
+  void set_incoming_message_processor(
+      scoped_ptr<BlimpMessageProcessor> processor);
+
+  // Gets a processor for BrowserSession->BlimpConnection message routing.
+  scoped_ptr<BlimpMessageProcessor> take_outgoing_message_processor() const;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(BlimpConnection);
 };