Add interfaces for most major Blimp net components.

blimp/engine/browser/blimp_browser_main_parts.cc

Index: blimp/engine/browser/blimp_browser_main_parts.cc
diff --git a/blimp/engine/browser/blimp_browser_main_parts.cc b/blimp/engine/browser/blimp_browser_main_parts.cc
index 232d8120d3b66e902ec1731f47d7f97d2091d338..3a9f91c65ed2c3f9544d91a7a6e1be2f7c86b4bf 100644
--- a/blimp/engine/browser/blimp_browser_main_parts.cc
+++ b/blimp/engine/browser/blimp_browser_main_parts.cc
@@ -45,11 +45,11 @@ void BlimpBrowserMainParts::PreMainMessageLoopRun() {
   BlimpMessage message;
   message.set_type(BlimpMessage::CONTROL);
   message.mutable_control()->set_type(ControlMessage::CREATE_TAB);
-  engine_session_->OnBlimpMessage(message);
+  engine_session_->ProcessMessage(message, net::CompletionCallback());
   message.mutable_control()->set_type(ControlMessage::LOAD_URL);
   message.mutable_control()->mutable_load_url()->set_url(
       "https://www.google.com/");
-  engine_session_->OnBlimpMessage(message);
+  engine_session_->ProcessMessage(message, net::CompletionCallback());
 }
 
 void BlimpBrowserMainParts::PostMainMessageLoopRun() {