DevTools: create test infrastructure so devtools drives the test

content/shell/browser/layout_test/blink_test_controller.h

Index: content/shell/browser/layout_test/blink_test_controller.h
diff --git a/content/shell/browser/layout_test/blink_test_controller.h b/content/shell/browser/layout_test/blink_test_controller.h
index d3f4eff788c74bf29c2734bd23be13b4791dbac7..05c300cc30dd3334ecc8256127b18b2b9fd9e9c6 100644
--- a/content/shell/browser/layout_test/blink_test_controller.h
+++ b/content/shell/browser/layout_test/blink_test_controller.h
@@ -195,6 +195,7 @@ class BlinkTestController : public base::NonThreadSafe,
 
   static BlinkTestController* instance_;
 
+  void LoadDevToolsJSTest();
   void DiscardMainWindow();
 
   // Message handlers.
@@ -232,6 +233,7 @@ class BlinkTestController : public base::NonThreadSafe,
   base::FilePath temp_path_;
 
   Shell* main_window_;
+  Shell* secondary_window_;
   Shell* devtools_window_;
 
   std::unique_ptr<LayoutTestDevToolsBindings> devtools_bindings_;