[Blimp] Refactor Blimp test engine with embedded test server and URL rewriting

blimp/engine/testing/session/test_blimp_engine_session.h

Index: blimp/engine/testing/session/test_blimp_engine_session.h
diff --git a/blimp/engine/testing/session/test_blimp_engine_session.h b/blimp/engine/testing/session/test_blimp_engine_session.h
new file mode 100644
index 0000000000000000000000000000000000000000..610643ec2b8202f916e83ae29f5c6507cb11d155
--- /dev/null
+++ b/blimp/engine/testing/session/test_blimp_engine_session.h
@@ -0,0 +1,36 @@
+// Copyright 2016 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_ENGINE_TESTING_SESSION_TEST_BLIMP_ENGINE_SESSION_H_
+#define BLIMP_ENGINE_TESTING_SESSION_TEST_BLIMP_ENGINE_SESSION_H_
+
+#include "blimp/engine/common/blimp_browser_context.h"
+#include "blimp/engine/session/blimp_engine_session.h"
+
+namespace blimp {
+namespace engine {
+
+// Blimp testing implementation of BlimpEngineSession. Class to extend
+// class BlimpEngineSession for testing. This rewrites the passed in
+// Blimp message url if necessary.
+class TestBlimpEngineSession : public BlimpEngineSession {
+ public:
+  TestBlimpEngineSession(
+      std::unique_ptr<BlimpBrowserContext> browser_context,
+      net::NetLog* net_log,
+      BlimpEngineConfig* config,
+      SettingsManager* settings_manager);
+  ~TestBlimpEngineSession() = default;
+
+  // Override BlimpEngineSession::BlimpEngineSession
+  // This object handles NavigationMessage::LOAD_URL
+  // url rewritting with testing url handler.
+  void ProcessMessage(std::unique_ptr<BlimpMessage> message,
+                      const net::CompletionCallback& callback) override;
+};
+
+}  // namespace engine
+}  // namespace blimp
+
+#endif  // BLIMP_ENGINE_TESTING_SESSION_TEST_BLIMP_ENGINE_SESSION_H_