Revert of [DevTools] Use InspectorFrontendHost.readyForTest for layout tests.

content/shell/browser/shell_devtools_frontend.h

Index: content/shell/browser/shell_devtools_frontend.h
diff --git a/content/shell/browser/shell_devtools_frontend.h b/content/shell/browser/shell_devtools_frontend.h
index 3258a5ac53851fbb986ef5ffacbdd61423a7b55c..b1be4a646b48d6c841fda69b26eb83522ce27fa9 100644
--- a/content/shell/browser/shell_devtools_frontend.h
+++ b/content/shell/browser/shell_devtools_frontend.h
@@ -55,13 +55,14 @@
   void DispatchProtocolMessage(DevToolsAgentHost* agent_host,
                                const std::string& message) override;
   base::DictionaryValue* preferences() { return &preferences_; }
-  virtual void HandleMessageFromDevToolsFrontend(const std::string& message);
 
  private:
   // WebContentsObserver overrides
   void RenderViewCreated(RenderViewHost* render_view_host) override;
   void DocumentAvailableInMainFrame() override;
   void WebContentsDestroyed() override;
+
+  void HandleMessageFromDevToolsFrontend(const std::string& message);
 
   // net::URLFetcherDelegate overrides.
   void OnURLFetchComplete(const net::URLFetcher* source) override;