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

blimp/engine/app/blimp_browser_main_parts.h

Index: blimp/engine/app/blimp_browser_main_parts.h
diff --git a/blimp/engine/app/blimp_browser_main_parts.h b/blimp/engine/app/blimp_browser_main_parts.h
index 0fdbe8a68f90f0fb80eaf33f82c4753766a759d2..fffc261261dc47ae6dcc3d224fc09c726c1de030 100644
--- a/blimp/engine/app/blimp_browser_main_parts.h
+++ b/blimp/engine/app/blimp_browser_main_parts.h
@@ -36,17 +36,23 @@ class BlimpBrowserMainParts : public content::BrowserMainParts {
   explicit BlimpBrowserMainParts(const content::MainFunctionParams& parameters);
   ~BlimpBrowserMainParts() override;
 
-  // content::BrowserMainParts implementation.
-  void PreEarlyInitialization() override;
-  void PreMainMessageLoopRun() override;
-  void PostMainMessageLoopRun() override;
-
   BlimpBrowserContext* GetBrowserContext();
   SettingsManager* GetSettingsManager();
   BlobChannelSender* GetBlobChannelSender();
   BlobChannelService* GetBlobChannelService();
   BlimpEngineSession* GetBlimpEngineSession();
 
+  // content::BrowserMainParts implementation.
+  void PreEarlyInitialization() override;
+  void PreMainMessageLoopRun() override;
+  void PostMainMessageLoopRun() override;
+
+ protected:
+  void SetSettingsManagerForTesting(
+      std::unique_ptr<SettingsManager> settings_manager);
+  void SetEngineSessionForTesting(
+      std::unique_ptr<BlimpEngineSession> engine_session);
+
  private:
   std::unique_ptr<BlimpEngineConfig> engine_config_;
   std::unique_ptr<net::NetLog> net_log_;