Requery the autofill server when forms and input fields are dynamically added.

components/autofill/browser/autofill_manager.cc

Index: components/autofill/browser/autofill_manager.cc
diff --git a/components/autofill/browser/autofill_manager.cc b/components/autofill/browser/autofill_manager.cc
index 3db909be9cc945cfbf022a187e50ae246b2f082c..a13ada31809bcf7482ae7ac544bff0f9f20a3204 100644
--- a/components/autofill/browser/autofill_manager.cc
+++ b/components/autofill/browser/autofill_manager.cc
@@ -448,14 +448,22 @@ bool AutofillManager::OnFormSubmitted(const FormData& form,
 
 void AutofillManager::OnFormsSeen(const std::vector<FormData>& forms,
                                   const TimeTicks& timestamp,
-                                  bool has_more_forms) {
+                                  autofill::FormsSeenParam param) {
+  bool is_post_document_load = param & autofill::DYNAMIC_FORMS_SEEN;
+  bool has_more_forms = param & autofill::PARTIAL_FORMS_SEEN;
+  // If new forms were added via AJAX or DHML, treat as new page.
+  if (is_post_document_load)
+    Reset();
+
   RenderViewHost* host = web_contents()->GetRenderViewHost();
   if (!host)
     return;
 
   if (!GetAutocheckoutURLPrefix().empty()) {
-    host->Send(
-        new AutofillMsg_WhitelistedForAutocheckout(host->GetRoutingID()));
+    if (!is_post_document_load) {
+      host->Send(
+          new AutofillMsg_WhitelistedForAutocheckout(host->GetRoutingID()));
+    }
     // If whitelisted URL, fetch all the forms.
     if (has_more_forms) {
       host->Send(new AutofillMsg_GetAllForms(host->GetRoutingID()));