WebUI: Add JavaScript lifecycle-control to WebUIMessageHandler.

content/public/test/test_web_ui.h

Index: content/public/test/test_web_ui.h
diff --git a/content/public/test/test_web_ui.h b/content/public/test/test_web_ui.h
index 9490d70418a9a3de779b98561f7067e03ab08ce0..eedd787821e4ea332bc0395cce8b27090e2bbbf8 100644
--- a/content/public/test/test_web_ui.h
+++ b/content/public/test/test_web_ui.h
@@ -44,6 +44,7 @@ class TestWebUI : public WebUI {
   void ProcessWebUIMessage(const GURL& source_url,
                            const std::string& message,
                            const base::ListValue& args) override {}
+  bool CanCallJavascript() override;
   void CallJavascriptFunction(const std::string& function_name) override;
   void CallJavascriptFunction(const std::string& function_name,
                               const base::Value& arg1) override;