Add interfaces for most major Blimp net components.

blimp/net/blimp_message_dispatcher.cc

Index: blimp/net/blimp_message_dispatcher.cc
diff --git a/blimp/net/blimp_message_dispatcher.cc b/blimp/net/blimp_message_dispatcher.cc
index 8c07c9f3bd566feecc9bf98fb637c6af2bea085d..4e385195480c5da10d852e432905daa6b43c0475 100644
--- a/blimp/net/blimp_message_dispatcher.cc
+++ b/blimp/net/blimp_message_dispatcher.cc
@@ -7,6 +7,7 @@
 #include <string>
 
 #include "base/strings/stringprintf.h"
+#include "net/base/net_errors.h"
 
 namespace blimp {
 namespace {
@@ -22,7 +23,7 @@ BlimpMessageDispatcher::BlimpMessageDispatcher() {}
 BlimpMessageDispatcher::~BlimpMessageDispatcher() {}
 
 void BlimpMessageDispatcher::AddReceiver(BlimpMessage::Type type,
-                                         BlimpMessageReceiver* receiver) {
+                                         BlimpMessageProcessor* receiver) {
   DCHECK(receiver);
   if (feature_receiver_map_.find(type) == feature_receiver_map_.end()) {
     feature_receiver_map_.insert(std::make_pair(type, receiver));
@@ -31,15 +32,17 @@ void BlimpMessageDispatcher::AddReceiver(BlimpMessage::Type type,
   }
 }
 
-net::Error BlimpMessageDispatcher::OnBlimpMessage(const BlimpMessage& message) {
+void BlimpMessageDispatcher::ProcessMessage(
+    const BlimpMessage& message,
+    const net::CompletionCallback& callback) {
   auto receiver_iter = feature_receiver_map_.find(message.type());
   if (receiver_iter == feature_receiver_map_.end()) {
     DLOG(FATAL) << "No registered receiver for "
                 << BlimpMessageToDebugString(message) << ".";
-    return net::ERR_NOT_IMPLEMENTED;
+    callback.Run(net::ERR_NOT_IMPLEMENTED);
   }
 
-  return receiver_iter->second->OnBlimpMessage(message);
+  receiver_iter->second->ProcessMessage(message, callback);
 }
 
 }  // namespace blimp