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

content/browser/frame_host/navigation_request.cc

Index: content/browser/frame_host/navigation_request.cc
diff --git a/content/browser/frame_host/navigation_request.cc b/content/browser/frame_host/navigation_request.cc
index 8feb8e20b4703844c6e6de8b98378b9c01a30f04..149ba26998cf75a2bebecb3752a4f4a3b7c7d0fe 100644
--- a/content/browser/frame_host/navigation_request.cc
+++ b/content/browser/frame_host/navigation_request.cc
@@ -306,6 +306,13 @@ void NavigationRequest::CreateNavigationHandle(int pending_nav_entry_id) {
       false,  // is_srcdoc
       common_params_.navigation_start, pending_nav_entry_id,
       false);  // started_in_context_menu
+
+  if (!begin_params_.searchable_form_url.is_empty()) {
+    navigation_handle_->set_searchable_form_url(
+        begin_params_.searchable_form_url);
+    navigation_handle_->set_searchable_form_encoding(
+        begin_params_.searchable_form_encoding);
+  }
 }
 
 void NavigationRequest::TransferNavigationHandleOwnership(