Bug 1958965 - Change scroll event setup to match the spec better. r=smaug

This matches the spec (plus resolution at
https://github.com/w3c/csswg-drafts/issues/11164) better, by running the
events per document.

Same comments as D244655 regarding the delayed event stuff that's going
away.

Differential Revision: https://phabricator.services.mozilla.com/D244666

dom/base/Document.cpp

@@ -1424,7 +1424,6 @@ Document::Document(const char* aContentType)
       mParserAborted(false),
       mReportedDocumentUseCounters(false),
       mHasReportedShadowDOMUsage(false),
-      mHasDelayedRefreshEvent(false),
       mLoadEventFiring(false),
       mSkipLoadEventAfterClose(false),
       mDisableCookieAccess(false),
@@ -13219,19 +13218,6 @@ void Document::UnsuppressEventHandlingAndFireEvents(bool aFireEvents) {
       for (net::ChannelEventQueue* queue : queues) {
         queue->Resume();
       }
-
-      // If there have been any events driven by the refresh driver which were
-      // delayed due to events being suppressed in this document, make sure
-      // there is a refresh scheduled soon so the events will run.
-      if (doc->mHasDelayedRefreshEvent) {
-        doc->mHasDelayedRefreshEvent = false;
-
-        if (doc->mPresShell) {
-          nsRefreshDriver* rd =
-              doc->mPresShell->GetPresContext()->RefreshDriver();
-          rd->RunDelayedEventsSoon();
-        }
-      }
     }
   }
 

dom/base/Document.h

@@ -2810,8 +2810,6 @@ class Document : public nsINode,
    */
   void FireOrClearPostMessageEvents(bool aFireEvents);
 
-  void SetHasDelayedRefreshEvent() { mHasDelayedRefreshEvent = true; }
-
   /**
    * Flag whether we're about to fire the window's load event for this document.
    */
@@ -4920,10 +4918,6 @@ class Document : public nsINode,
 
   bool mHasReportedShadowDOMUsage : 1;
 
-  // Whether an event triggered by the refresh driver was delayed because this
-  // document has suppressed events.
-  bool mHasDelayedRefreshEvent : 1;
-
   // The HTML spec has a "iframe load in progress" flag, but that doesn't seem
   // to have the right semantics.  See
   // <https://github.com/whatwg/html/issues/4292>. What we have instead is a

dom/base/VisualViewport.cpp

@@ -216,7 +216,7 @@ VisualViewport::VisualViewportScrollEvent::VisualViewportScrollEvent(
       mPrevLayoutOffset(aPrevLayoutOffset) {
   VVP_LOG("%p: Registering PostScroll on %p %p\n", aViewport, aPresContext,
           aPresContext->RefreshDriver());
-  aPresContext->RefreshDriver()->PostScrollEvent(this);
+  aPresContext->PresShell()->PostScrollEvent(this);
 }
 
 bool VisualViewport::VisualViewportScrollEvent::HasPresContext(

layout/base/PresShell.cpp

@@ -1997,6 +1997,16 @@ bool PresShell::CanHandleUserInputEvents(WidgetGUIEvent* aGUIEvent) {
   return true;
 }
 
+void PresShell::PostScrollEvent(Runnable* aEvent) {
+  MOZ_ASSERT(aEvent);
+  const bool hadEvents = !mPendingScrollEvents.IsEmpty();
+  mPendingScrollEvents.AppendElement(aEvent);
+  if (!hadEvents) {
+    mPresContext->RefreshDriver()->ScheduleRenderingPhase(
+        RenderingPhase::ScrollSteps);
+  }
+}
+
 void PresShell::ScheduleResizeEventIfNeeded(ResizeEventKind aKind) {
   if (mIsDestroying) {
     return;
@@ -2011,7 +2021,7 @@ void PresShell::ScheduleResizeEventIfNeeded(ResizeEventKind aKind) {
     mVisualViewportResizeEventPending = true;
   }
   mPresContext->RefreshDriver()->ScheduleRenderingPhase(
-        mozilla::RenderingPhase::ResizeSteps);
+      RenderingPhase::ResizeSteps);
 }
 
 bool PresShell::ResizeReflowIgnoreOverride(nscoord aWidth, nscoord aHeight,
@@ -2165,6 +2175,19 @@ void PresShell::RunResizeSteps() {
   }
 }
 
+// https://drafts.csswg.org/cssom-view/#document-run-the-scroll-steps
+// But note: https://github.com/w3c/csswg-drafts/issues/11164
+void PresShell::RunScrollSteps() {
+  // Scroll events are one-shot, so after running them we can drop them.
+  // However, dispatching a scroll event can potentially cause more scroll
+  // events to be posted, so we move the initial set into a temporary array
+  // first. (Newly posted scroll events will be dispatched on the next tick.)
+  auto events = std::move(mPendingScrollEvents);
+  for (auto& event : events) {
+    event->Run();
+  }
+}
+
 static nsIContent* GetNativeAnonymousSubtreeRoot(nsIContent* aContent) {
   if (!aContent) {
     return nullptr;

layout/base/PresShell.h

@@ -361,6 +361,8 @@ class PresShell final : public nsStubDocumentObserver,
   enum class ResizeEventKind : uint8_t { Regular, Visual };
   void ScheduleResizeEventIfNeeded(ResizeEventKind = ResizeEventKind::Regular);
 
+  void PostScrollEvent(mozilla::Runnable*);
+
   /**
    * Returns true if the document hosted by this presShell is in a devtools
    * Responsive Design Mode browsing context.
@@ -1175,6 +1177,7 @@ class PresShell final : public nsStubDocumentObserver,
   bool HasHandledUserInput() const { return mHasHandledUserInput; }
 
   MOZ_CAN_RUN_SCRIPT void RunResizeSteps();
+  MOZ_CAN_RUN_SCRIPT void RunScrollSteps();
 
   void NativeAnonymousContentWillBeRemoved(nsIContent* aAnonContent);
 
@@ -3101,6 +3104,8 @@ class PresShell final : public nsStubDocumentObserver,
   nsTHashSet<ScrollContainerFrame*> mPendingScrollAnchorSelection;
   nsTHashSet<ScrollContainerFrame*> mPendingScrollAnchorAdjustment;
   nsTHashSet<ScrollContainerFrame*> mPendingScrollResnap;
+  // Pending list of scroll/scrollend/etc events.
+  nsTArray<RefPtr<Runnable>> mPendingScrollEvents;
 
   nsTHashSet<nsIContent*> mHiddenContentInForcedLayout;
 

layout/base/nsRefreshDriver.cpp

@@ -1556,27 +1556,6 @@ bool nsRefreshDriver::RemoveRefreshObserver(nsARefreshObserver* aObserver,
   return true;
 }
 
-void nsRefreshDriver::PostScrollEvent(mozilla::Runnable* aScrollEvent,
-                                      bool aDelayed) {
-  if (aDelayed) {
-    mDelayedScrollEvents.AppendElement(aScrollEvent);
-  } else {
-    mScrollEvents.AppendElement(aScrollEvent);
-    ScheduleRenderingPhase(RenderingPhase::ScrollSteps);
-  }
-}
-
-void nsRefreshDriver::DispatchScrollEvents() {
-  // Scroll events are one-shot, so after running them we can drop them.
-  // However, dispatching a scroll event can potentially cause more scroll
-  // events to be posted, so we move the initial set into a temporary array
-  // first. (Newly posted scroll events will be dispatched on the next tick.)
-  ScrollEventArray events = std::move(mScrollEvents);
-  for (auto& event : events) {
-    event->Run();
-  }
-}
-
 void nsRefreshDriver::AddPostRefreshObserver(
     nsAPostRefreshObserver* aObserver) {
   MOZ_ASSERT(!mPostRefreshObservers.Contains(aObserver));
@@ -1654,17 +1633,6 @@ void nsRefreshDriver::FlushForceNotifyContentfulPaintPresContext() {
   }
 }
 
-void nsRefreshDriver::RunDelayedEventsSoon() {
-  // Place entries for delayed events into their corresponding normal list,
-  // and schedule a refresh. When these delayed events run, if their document
-  // still has events suppressed then they will be readded to the delayed
-  // events list.
-
-  mScrollEvents.AppendElements(mDelayedScrollEvents);
-  mDelayedScrollEvents.Clear();
-  ScheduleRenderingPhase(RenderingPhase::ScrollSteps);
-}
-
 bool nsRefreshDriver::CanDoCatchUpTick() {
   if (mTestControllingRefreshes || !mActiveTimer) {
     return false;
@@ -2584,9 +2552,12 @@ void nsRefreshDriver::Tick(VsyncId aId, TimeStamp aNowTime,
                     });
 
   // Step 9. For each doc of docs, run the scroll steps for doc.
-  RunRenderingPhaseLegacy(
-      RenderingPhase::ScrollSteps,
-      [&]() MOZ_CAN_RUN_SCRIPT_BOUNDARY_LAMBDA { DispatchScrollEvents(); });
+  RunRenderingPhase(RenderingPhase::ScrollSteps,
+                    [](Document& aDoc) MOZ_CAN_RUN_SCRIPT_BOUNDARY_LAMBDA {
+                      if (RefPtr<PresShell> ps = aDoc.GetPresShell()) {
+                        ps->RunScrollSteps();
+                      }
+                    });
 
   // Step 10. For each doc of docs, evaluate media queries and report changes
   // for doc.

layout/base/nsRefreshDriver.h

@@ -26,7 +26,6 @@
 #include "nsThreadUtils.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/Maybe.h"
-#include "mozilla/dom/VisualViewport.h"
 #include "mozilla/layers/TransactionIdAllocator.h"
 #include "LayersTypes.h"
 
@@ -46,14 +45,17 @@ class PresShell;
 class RefreshDriverTimer;
 class Runnable;
 class Task;
+
+namespace dom {
+class Document;
+}
+
 }  // namespace mozilla
 
 class nsRefreshDriver final : public mozilla::layers::TransactionIdAllocator,
                               public nsARefreshObserver {
   using Document = mozilla::dom::Document;
   using TransactionId = mozilla::layers::TransactionId;
-  using VVPScrollEvent =
-      mozilla::dom::VisualViewport::VisualViewportScrollEvent;
   using LogPresShellObserver = mozilla::LogPresShellObserver;
 
  public:
@@ -105,8 +107,6 @@ class nsRefreshDriver final : public mozilla::layers::TransactionIdAllocator,
                              mozilla::FlushType aFlushType);
 
 
-  void PostScrollEvent(mozilla::Runnable* aScrollEvent, bool aDelayed = false);
-  void DispatchScrollEvents();
   MOZ_CAN_RUN_SCRIPT void FlushLayoutOnPendingDocsAndFixUpFocus();
 
   /**
@@ -341,9 +341,6 @@ class nsRefreshDriver final : public mozilla::layers::TransactionIdAllocator,
   static void DispatchIdleTaskAfterTickUnlessExists(mozilla::Task* aTask);
   static void CancelIdleTask(mozilla::Task* aTask);
 
-  // Schedule a refresh so that any delayed events will run soon.
-  void RunDelayedEventsSoon();
-
   void InitializeTimer() {
     MOZ_ASSERT(!mActiveTimer);
     EnsureTimerStarted();
@@ -420,7 +417,6 @@ class nsRefreshDriver final : public mozilla::layers::TransactionIdAllocator,
   void FinishedVsyncTick() { mAttemptedExtraTickSinceLastVsync = false; }
 
  private:
-  using ScrollEventArray = nsTArray<RefPtr<mozilla::Runnable>>;
   using RequestTable = nsTHashSet<RefPtr<imgIRequest>>;
   struct ImageStartData {
     ImageStartData() = default;
@@ -450,10 +446,10 @@ class nsRefreshDriver final : public mozilla::layers::TransactionIdAllocator,
   MOZ_CAN_RUN_SCRIPT
   void RunVideoAndFrameRequestCallbacks(mozilla::TimeStamp aNowTime);
   MOZ_CAN_RUN_SCRIPT
-  void RunVideoFrameCallbacks(const nsTArray<RefPtr<mozilla::dom::Document>>&,
+  void RunVideoFrameCallbacks(const nsTArray<RefPtr<Document>>&,
                               mozilla::TimeStamp aNowTime);
   MOZ_CAN_RUN_SCRIPT
-  void RunFrameRequestCallbacks(const nsTArray<RefPtr<mozilla::dom::Document>>&,
+  void RunFrameRequestCallbacks(const nsTArray<RefPtr<Document>>&,
                                 mozilla::TimeStamp aNowTime);
   void UpdateRemoteFrameEffects();
   void UpdateRelevancyOfContentVisibilityAutoFrames();
@@ -645,9 +641,6 @@ class nsRefreshDriver final : public mozilla::layers::TransactionIdAllocator,
   RequestTable mRequests;
   ImageStartTable mStartTable;
   AutoTArray<nsCOMPtr<nsIRunnable>, 16> mEarlyRunners;
-  ScrollEventArray mScrollEvents;
-  // Scroll events on documents that might have events suppressed.
-  ScrollEventArray mDelayedScrollEvents;
   AutoTArray<mozilla::PresShell*, 16> mStyleFlushObservers;
   nsTObserverArray<nsAPostRefreshObserver*> mPostRefreshObservers;
   nsTArray<mozilla::UniquePtr<mozilla::PendingFullscreenEvent>>

layout/generic/ScrollContainerFrame.cpp

@@ -159,7 +159,7 @@ static ScrollDirections GetOverflowChange(const nsRect& aCurScrolledRect,
 class ScrollContainerFrame::ScrollEvent : public Runnable {
  public:
   NS_DECL_NSIRUNNABLE
-  explicit ScrollEvent(ScrollContainerFrame* aHelper, bool aDelayed);
+  explicit ScrollEvent(ScrollContainerFrame* aHelper);
   void Revoke() { mHelper = nullptr; }
 
  private:
@@ -169,7 +169,7 @@ class ScrollContainerFrame::ScrollEvent : public Runnable {
 class ScrollContainerFrame::ScrollEndEvent : public Runnable {
  public:
   NS_DECL_NSIRUNNABLE
-  explicit ScrollEndEvent(ScrollContainerFrame* aHelper, bool aDelayed);
+  explicit ScrollEndEvent(ScrollContainerFrame* aHelper);
   void Revoke() { mHelper = nullptr; }
 
  private:
@@ -5382,30 +5382,20 @@ nsresult ScrollContainerFrame::FireScrollPortEvent() {
   return EventDispatcher::Dispatch(content, presContext, &event);
 }
 
-void ScrollContainerFrame::PostScrollEndEvent(bool aDelayed) {
+void ScrollContainerFrame::PostScrollEndEvent() {
   if (mScrollEndEvent) {
     return;
   }
 
-  // The ScrollEndEvent constructor registers itself with the refresh driver.
-  mScrollEndEvent = new ScrollEndEvent(this, aDelayed);
+  // The ScrollEndEvent constructor registers itself.
+  mScrollEndEvent = new ScrollEndEvent(this);
 }
 
 void ScrollContainerFrame::FireScrollEndEvent() {
-  RefPtr<nsIContent> content = GetContent();
-  MOZ_ASSERT(content);
-
   MOZ_ASSERT(mScrollEndEvent);
   mScrollEndEvent->Revoke();
   mScrollEndEvent = nullptr;
 
-  if (content->GetComposedDoc() &&
-      content->GetComposedDoc()->EventHandlingSuppressed()) {
-    content->GetComposedDoc()->SetHasDelayedRefreshEvent();
-    PostScrollEndEvent(/* aDelayed = */ true);
-    return;
-  }
-
   RefPtr<nsPresContext> presContext = PresContext();
   nsEventStatus status = nsEventStatus_eIgnore;
   WidgetGUIEvent event(true, eScrollend, nullptr);
@@ -5825,10 +5815,9 @@ void ScrollContainerFrame::CurPosAttributeChangedInternal(nsIContent* aContent,
 
 /* ============= Scroll events ========== */
 
-ScrollContainerFrame::ScrollEvent::ScrollEvent(ScrollContainerFrame* aHelper,
-                                               bool aDelayed)
+ScrollContainerFrame::ScrollEvent::ScrollEvent(ScrollContainerFrame* aHelper)
     : Runnable("ScrollContainerFrame::ScrollEvent"), mHelper(aHelper) {
-  mHelper->PresContext()->RefreshDriver()->PostScrollEvent(this, aDelayed);
+  mHelper->PresShell()->PostScrollEvent(this);
 }
 
 // TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230, bug 1535398)
@@ -5841,9 +5830,9 @@ ScrollContainerFrame::ScrollEvent::Run() {
 }
 
 ScrollContainerFrame::ScrollEndEvent::ScrollEndEvent(
-    ScrollContainerFrame* aHelper, bool aDelayed)
+    ScrollContainerFrame* aHelper)
     : Runnable("ScrollContainerFrame::ScrollEndEvent"), mHelper(aHelper) {
-  mHelper->PresContext()->RefreshDriver()->PostScrollEvent(this, aDelayed);
+  mHelper->PresShell()->PostScrollEvent(this);
 }
 
 MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHODIMP
@@ -5864,16 +5853,6 @@ void ScrollContainerFrame::FireScrollEvent() {
   mScrollEvent->Revoke();
   mScrollEvent = nullptr;
 
-  // If event handling is suppressed, keep posting the scroll event to the
-  // refresh driver until it is unsuppressed. The event is marked as delayed so
-  // that the refresh driver does not continue ticking.
-  if (content->GetComposedDoc() &&
-      content->GetComposedDoc()->EventHandlingSuppressed()) {
-    content->GetComposedDoc()->SetHasDelayedRefreshEvent();
-    PostScrollEvent(/* aDelayed = */ true);
-    return;
-  }
-
   bool oldProcessing = mProcessingScrollEvent;
   AutoWeakFrame weakFrame(this);
   auto RestoreProcessingScrollEvent = mozilla::MakeScopeExit([&] {
@@ -5903,13 +5882,13 @@ void ScrollContainerFrame::FireScrollEvent() {
   }
 }
 
-void ScrollContainerFrame::PostScrollEvent(bool aDelayed) {
+void ScrollContainerFrame::PostScrollEvent() {
   if (mScrollEvent) {
     return;
   }
 
-  // The ScrollEvent constructor registers itself with the refresh driver.
-  mScrollEvent = new ScrollEvent(this, aDelayed);
+  // The ScrollEvent constructor registers itself.
+  mScrollEvent = new ScrollEvent(this);
 }
 
 // TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230, bug 1535398)

layout/generic/ScrollContainerFrame.h

@@ -1083,7 +1083,7 @@ class ScrollContainerFrame : public nsContainerFrame,
   PhysicalAxes GetOverflowAxes() const;
 
   MOZ_CAN_RUN_SCRIPT nsresult FireScrollPortEvent();
-  void PostScrollEndEvent(bool aDelayed = false);
+  void PostScrollEndEvent();
   MOZ_CAN_RUN_SCRIPT void FireScrollEndEvent();
   void PostOverflowEvent();
 
@@ -1111,7 +1111,7 @@ class ScrollContainerFrame : public nsContainerFrame,
    */
   void CurPosAttributeChangedInternal(nsIContent*, bool aDoScroll = true);
 
-  void PostScrollEvent(bool aDelayed = false);
+  void PostScrollEvent();
   MOZ_CAN_RUN_SCRIPT void FireScrollEvent();
   void PostScrolledAreaEvent();
   MOZ_CAN_RUN_SCRIPT void FireScrolledAreaEvent();