PlzNavigate: send searchable form data to the browser side on form submission.

content/common/navigation_params.h

Index: content/common/navigation_params.h
diff --git a/content/common/navigation_params.h b/content/common/navigation_params.h
index ec5ec419118524efed1c9ebb93fdd39c62d59a8a..98757a7303b941944faab686f576dac7240c021c 100644
--- a/content/common/navigation_params.h
+++ b/content/common/navigation_params.h
@@ -163,6 +163,10 @@ struct CONTENT_EXPORT BeginNavigationParams {
 
   // Indicates the request context type.
   RequestContextType request_context_type;
+
+  // See WebSearchableFormData for a description of these.
+  GURL searchable_form_url;
+  std::string searchable_form_encoding;
 };
 
 // Provided by the browser -----------------------------------------------------