Bug 1518442 - Part 3: Add dom.formdata.event.enabled preference for Event-based form participation; r=smaug,edgar

Differential Revision: https://phabricator.services.mozilla.com/D43987

--HG--
extra : moz-landing-system : lando

dom/base/FormData.cpp

@@ -306,7 +306,9 @@ already_AddRefed<FormData> FormData::Constructor(
 
     // Step 9. Return a shallow clone of entry list.
     // https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#constructing-form-data-set
-    formData = formData->Clone();
+    if (StaticPrefs::dom_formdata_event_enabled()) {
+      formData = formData->Clone();
+    }
   }
 
   return formData.forget();

dom/base/nsContentUtils.cpp

@@ -3808,7 +3808,11 @@ nsIContentPolicy* nsContentUtils::GetContentPolicy() {
 // static
 bool nsContentUtils::IsEventAttributeName(nsAtom* aName, int32_t aType) {
   const char16_t* name = aName->GetUTF16String();
-  if (name[0] != 'o' || name[1] != 'n') return false;
+  if (name[0] != 'o' || name[1] != 'n' ||
+      (aName == nsGkAtoms::onformdata &&
+       !mozilla::StaticPrefs::dom_formdata_event_enabled())) {
+    return false;
+  }
 
   EventNameMapping mapping;
   return (sAtomEventTable->Get(aName, &mapping) && mapping.mType & aType);

dom/events/test/test_all_synthetic_events.html

@@ -477,7 +477,8 @@ function test() {
 
 SimpleTest.waitForExplicitFinish();
 SpecialPowers.pushPrefEnv(
-  {"set": [["dom.w3c_touch_events.legacy_apis.enabled", true]]},
+  {"set": [["dom.w3c_touch_events.legacy_apis.enabled", true],
+           ["dom.formdata.event.enabled", true]]},
   function() {
     test();
     SimpleTest.finish();

dom/html/HTMLFormElement.cpp

@@ -560,7 +560,8 @@ nsresult HTMLFormElement::DoSubmit(WidgetEvent* aEvent) {
   nsresult rv = BuildSubmission(getter_Transfers(submission), aEvent);
 
   // Don't raise an error if form cannot navigate.
-  if (rv == NS_ERROR_NOT_AVAILABLE) {
+  if (StaticPrefs::dom_formdata_event_enabled() &&
+      rv == NS_ERROR_NOT_AVAILABLE) {
     mIsSubmitting = false;
     return NS_OK;
   }
@@ -628,7 +629,7 @@ nsresult HTMLFormElement::BuildSubmission(HTMLFormSubmission** aFormSubmission,
 
   // Step 9. If form cannot navigate, then return.
   // https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#form-submission-algorithm
-  if (!GetComposedDoc()) {
+  if (StaticPrefs::dom_formdata_event_enabled() && !GetComposedDoc()) {
     return NS_ERROR_NOT_AVAILABLE;
   }
 
@@ -885,7 +886,8 @@ nsresult HTMLFormElement::NotifySubmitObservers(nsIURI* aActionURL,
 
 nsresult HTMLFormElement::ConstructEntryList(FormData* aFormData) {
   MOZ_ASSERT(aFormData, "Must have FormData!");
-  if (mIsConstructingEntryList) {
+  bool isFormDataEventEnabled = StaticPrefs::dom_formdata_event_enabled();
+  if (isFormDataEventEnabled && mIsConstructingEntryList) {
     // Step 2.2 of https://xhr.spec.whatwg.org/#dom-formdata.
     return NS_ERROR_DOM_INVALID_STATE_ERR;
   }
@@ -908,16 +910,18 @@ nsresult HTMLFormElement::ConstructEntryList(FormData* aFormData) {
     sortedControls[i]->SubmitNamesValues(aFormData);
   }
 
-  FormDataEventInit init;
-  init.mBubbles = true;
-  init.mCancelable = false;
-  init.mFormData = aFormData;
-  RefPtr<FormDataEvent> event =
-      FormDataEvent::Constructor(this, NS_LITERAL_STRING("formdata"), init);
-  event->SetTrusted(true);
+  if (isFormDataEventEnabled) {
+    FormDataEventInit init;
+    init.mBubbles = true;
+    init.mCancelable = false;
+    init.mFormData = aFormData;
+    RefPtr<FormDataEvent> event =
+        FormDataEvent::Constructor(this, NS_LITERAL_STRING("formdata"), init);
+    event->SetTrusted(true);
 
-  EventDispatcher::DispatchDOMEvent(ToSupports(this), nullptr, event, nullptr,
-                                    nullptr);
+    EventDispatcher::DispatchDOMEvent(ToSupports(this), nullptr, event, nullptr,
+                                      nullptr);
+  }
 
   return NS_OK;
 }

dom/tests/mochitest/general/test_interfaces.js

@@ -384,7 +384,7 @@ var interfaceNamesInGlobalScope = [
   // IMPORTANT: Do not change this list without review from a DOM peer!
   { name: "FormData", insecureContext: true },
   // IMPORTANT: Do not change this list without review from a DOM peer!
-  { name: "FormDataEvent", insecureContext: true },
+  { name: "FormDataEvent", insecureContext: true, nightly: true },
   // IMPORTANT: Do not change this list without review from a DOM peer!
   { name: "FontFace", insecureContext: true },
   // IMPORTANT: Do not change this list without review from a DOM peer!

dom/webidl/EventHandler.webidl

@@ -50,6 +50,7 @@ interface mixin GlobalEventHandlers {
            attribute EventHandler ondurationchange;
            attribute EventHandler onemptied;
            attribute EventHandler onended;
+           [Pref="dom.formdata.event.enabled"]
            attribute EventHandler onformdata;
            attribute EventHandler oninput;
            attribute EventHandler oninvalid;

dom/webidl/FormDataEvent.webidl

@@ -8,7 +8,8 @@
  */
 
 [Exposed=Window,
- Constructor(DOMString type, optional FormDataEventInit eventInitDict = {})]
+ Constructor(DOMString type, optional FormDataEventInit eventInitDict = {}),
+ Pref="dom.formdata.event.enabled"]
 interface FormDataEvent : Event {
   // C++ can't deal with a method called FormData() in the generated code
   [BinaryName="GetFormData"]

modules/libpref/init/StaticPrefList.yaml

@@ -1459,6 +1459,12 @@
   value: false
   mirror: always
 
+# Whether or not formData event is enabled.
+- name: dom.formdata.event.enabled
+  type: bool
+  value: @IS_NIGHTLY_BUILD@
+  mirror: always
+
 # Support @autocomplete values for form autofill feature.
 - name: dom.forms.autocomplete.formautofill
   type: bool

testing/web-platform/meta/html/semantics/forms/form-submission-0/__dir__.ini

@@ -0,0 +1 @@
+prefs: [dom.formdata.event.enabled:true]

testing/web-platform/meta/html/webappapis/scripting/events/__dir__.ini

@@ -0,0 +1 @@
+prefs: [dom.formdata.event.enabled:true]

testing/web-platform/meta/xhr/__dir__.ini

@@ -1 +1 @@
-prefs: [javascript.options.streams:true, dom.xhr.standard_content_type_normalization:true]
+prefs: [javascript.options.streams:true, dom.xhr.standard_content_type_normalization:true, dom.formdata.event.enabled:true]

testing/web-platform/tests/html/dom/__dir__.ini

@@ -0,0 +1 @@
+prefs: [dom.formdata.event.enabled:true]