[Password Manager] Use successful XHR submission as a signal for password saving

components/autofill/content/renderer/password_autofill_agent.h

Index: components/autofill/content/renderer/password_autofill_agent.h
diff --git a/components/autofill/content/renderer/password_autofill_agent.h b/components/autofill/content/renderer/password_autofill_agent.h
index 720f97bbc7ab1d3485c7490e11aeedb8e0d0ee06..4609930eefb4b9b464d88fde2d4675c368c8b71c 100644
--- a/components/autofill/content/renderer/password_autofill_agent.h
+++ b/components/autofill/content/renderer/password_autofill_agent.h
@@ -64,6 +64,10 @@ class PasswordAutofillAgent : public content::RenderFrameObserver {
   // Called when new form controls are inserted.
   void OnDynamicFormsSeen();
 
+  // Called when an XHR has succesfully completed. Used to determine if
+  // a form has been submitted by XHR without navigation.
+  void XHRSucceeded();
+
   // Called when the user first interacts with the page after a load. This is a
   // signal to make autofilled values of password input elements accessible to
   // JavaScript.
@@ -226,6 +230,10 @@ class PasswordAutofillAgent : public content::RenderFrameObserver {
   void ProvisionallySavePassword(const blink::WebFormElement& form,
                                  ProvisionallySaveRestriction restriction);
 
+  // Returns true if |provisionally_saved_form_| has enough information that
+  // it is likely filled out.
+  bool ProvisionallySavedPasswordIsValid();
+
   // Passes through |RenderViewObserver| method to |this|.
   LegacyPasswordAutofillAgent legacy_;