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

blimp/engine/app/blimp_content_browser_client.h

Index: blimp/engine/app/blimp_content_browser_client.h
diff --git a/blimp/engine/app/blimp_content_browser_client.h b/blimp/engine/app/blimp_content_browser_client.h
index 20a2a7d2bf2cbecb2ca1b3442957d5d70a7ce5fc..5591f1962faa503665da3d3b0a7882f91ed09941 100644
--- a/blimp/engine/app/blimp_content_browser_client.h
+++ b/blimp/engine/app/blimp_content_browser_client.h
@@ -23,6 +23,8 @@ class BlimpContentBrowserClient : public content::ContentBrowserClient {
     return blimp_browser_main_parts_;
   }
 
+  BlimpBrowserContext* GetBrowserContext();
+
   // content::ContentBrowserClient implementation.
   content::BrowserMainParts* CreateBrowserMainParts(
       const content::MainFunctionParams& parameters) override;
@@ -34,7 +36,9 @@ class BlimpContentBrowserClient : public content::ContentBrowserClient {
   std::unique_ptr<base::Value> GetServiceManifestOverlay(
       base::StringPiece name) override;
 
-  BlimpBrowserContext* GetBrowserContext();
+ protected:
+  void SetBrowserMainPartsForTesting(
+      BlimpBrowserMainParts* blimp_browser_main_parts);
 
  private:
   // Owned by BrowserMainLoop