Bug 1863801 - P2. Add DOMFormRemoved event listener after successful fetch or XHR request r=dimi

Differential Revision: https://phabricator.services.mozilla.com/D193308

dom/base/Document.h

@@ -3781,7 +3781,8 @@ class Document : public nsINode,
   void SetNotifyFetchSuccess(bool aShouldNotify);
 
   // When this is set, removing a form or a password field from DOM
-  // sends a Chrome-only event. This is now only used by the password manager.
+  // sends a Chrome-only event. This is now only used by the password manager
+  // and formautofill.
   void SetNotifyFormOrPasswordRemoved(bool aShouldNotify);
 
   // This function is used by HTMLFormElement and HTMLInputElement to determin

dom/html/HTMLFormElement.cpp

@@ -2072,9 +2072,9 @@ void HTMLFormElement::MaybeFireFormRemoved() {
     return;
   }
 
-  // Right now, only the password manager listens to the event and only listen
-  // to it under certain circumstances. So don't fire this event unless
-  // necessary.
+  // Right now, only the password manager and formautofill listen to the event
+  // and only listen to it under certain circumstances. So don't fire this event
+  // unless necessary.
   if (!doc->ShouldNotifyFormOrPasswordRemoved()) {
     return;
   }

dom/html/HTMLFormElement.h

@@ -593,7 +593,7 @@ class HTMLFormElement final : public nsGenericHTMLElement,
 
   /**
    * Fire an event when the form is removed from the DOM tree. This is now only
-   * used by the password manager.
+   * used by the password manager and formautofill.
    */
   void MaybeFireFormRemoved();
 

dom/html/HTMLInputElement.h

@@ -1636,7 +1636,7 @@ class HTMLInputElement final : public TextControlElement,
 
   /**
    * Fire an event when the password input field is removed from the DOM tree.
-   * This is now only used by the password manager.
+   * This is now only used by the password manager and formautofill.
    */
   void MaybeFireInputPasswordRemoved();
 

toolkit/components/formautofill/FormAutofillChild.sys.mjs

@@ -122,6 +122,23 @@ export class FormAutofillChild extends JSWindowActorChild {
     );
   }
 
+  /**
+   * After a DOMDocFetchSuccess event, we register an event listener for the DOMFormRemoved event
+   *
+   * @param {Document} document The document we want to be notified by of a DOMFormRemoved event
+   */
+  registerDOMFormRemovedEventListener(document) {
+    document.setNotifyFormOrPasswordRemoved(true);
+
+    // Is removed after a DOMFormRemoved event (bug 1864855)
+    /* eslint-disable mozilla/balanced-listeners */
+    this.docShell.chromeEventHandler.addEventListener(
+      "DOMFormRemoved",
+      this,
+      true
+    );
+  }
+
   /**
    * After a DOMDocFetchSuccess event we remove the DOMDocFetchSuccess event listener
    *
@@ -135,6 +152,19 @@ export class FormAutofillChild extends JSWindowActorChild {
     );
   }
 
+  /**
+   * After a DOMFormRemoved event we remove the DOMFormRemoved event listener
+   *
+   * @param {Document} document The document we are notified by of a DOMFormRemoved event
+   */
+  unregisterDOMFormRemovedEventListener(document) {
+    document.setNotifyFormOrPasswordRemoved(false);
+    this.docShell.chromeEventHandler.removeEventListener(
+      "DOMFormRemoved",
+      this
+    );
+  }
+
   shouldIgnoreFormAutofillEvent(event) {
     let nodePrincipal = event.target.nodePrincipal;
     return (
@@ -148,7 +178,6 @@ export class FormAutofillChild extends JSWindowActorChild {
     if (!evt.isTrusted) {
       return;
     }
-
     if (this.shouldIgnoreFormAutofillEvent(evt)) {
       return;
     }
@@ -166,6 +195,10 @@ export class FormAutofillChild extends JSWindowActorChild {
         }
         break;
       }
+      case "DOMFormRemoved": {
+        this.onDOMFormRemoved(evt);
+        break;
+      }
       case "DOMDocFetchSuccess": {
         this.onDOMDocFetchSuccess(evt);
         break;
@@ -213,13 +246,25 @@ export class FormAutofillChild extends JSWindowActorChild {
   onDOMFormBeforeSubmit(evt) {
     let formElement = evt.target;
 
-    if (!lazy.FormAutofill.isAutofillEnabled) {
-      return;
-    }
-
     lazy.FormAutofillContent.formSubmitted(formElement);
   }
 
+  /**
+   * Handle the DOMFormRemoved event.
+   *
+   * Infers a form submission when the form is removed
+   * after a successful fetch or XHR request.
+   *
+   * @param {Event} evt DOMFormRemoved
+   */
+  onDOMFormRemoved(evt) {
+    const document = evt.composedTarget.ownerDocument;
+
+    // TODO: Infer a form submission (will be implemented P3)
+
+    this.unregisterDOMFormRemovedEventListener(document);
+  }
+
   /**
    * Handle the DOMDocFetchSuccess event.
    *
@@ -230,7 +275,8 @@ export class FormAutofillChild extends JSWindowActorChild {
    */
   onDOMDocFetchSuccess(evt) {
     const document = evt.target;
-    // TODO: Register mutation observer to watch for form removal (implemented in P2)
+
+    this.registerDOMFormRemovedEventListener(document);
 
     this.unregisterDOMDocFetchSuccessEventListener(document);
   }