Bug 1769774 - Stop tracking painted PresShells. r=mstange

After bug 1730284 we don't use it for throttling iframes, so the only
remaining use the test-only nsIDOMWindowUtils.paintCount. None of the
tests using it rely on the empty transaction case, so we should be able
to just remove this.

Differential Revision: https://phabricator.services.mozilla.com/D146589

layout/base/PresShell.cpp

@@ -6411,15 +6411,11 @@ void PresShell::PaintInternal(nsView* aViewToPaint, PaintInternalFlags aFlags) {
               (aFlags & PaintInternalFlags::PaintComposite)
                   ? WindowRenderer::END_DEFAULT
                   : WindowRenderer::END_NO_COMPOSITE)) {
-        frame->UpdatePaintCountForPaintedPresShells();
         return;
       }
     }
     frame->RemoveStateBits(NS_FRAME_UPDATE_LAYER_TREE);
   }
-  if (frame) {
-    frame->ClearPresShellsFromLastPaint();
-  }
 
   nscolor bgcolor = ComputeBackstopColor(aViewToPaint);
   PaintFrameFlags flags =

layout/generic/nsIFrame.cpp

@@ -11696,18 +11696,6 @@ nsIFrame::PhysicalAxes nsIFrame::ShouldApplyOverflowClipping(
   return clip ? PhysicalAxes::Both : PhysicalAxes::None;
 }
 
-void nsIFrame::AddPaintedPresShell(mozilla::PresShell* aPresShell) {
-  PaintedPresShellList()->AppendElement(do_GetWeakReference(aPresShell));
-}
-
-void nsIFrame::UpdatePaintCountForPaintedPresShells() {
-  for (nsWeakPtr& item : *PaintedPresShellList()) {
-    if (RefPtr<mozilla::PresShell> presShell = do_QueryReferent(item)) {
-      presShell->IncrementPaintCount();
-    }
-  }
-}
-
 #ifdef DEBUG
 static void GetTagName(nsIFrame* aFrame, nsIContent* aContent, int aResultSize,
                        char* aResult) {

layout/generic/nsIFrame.h

@@ -4441,24 +4441,6 @@ class nsIFrame : public nsQueryFrame {
    */
   virtual void PullOverflowsFromPrevInFlow() {}
 
-  /**
-   * Clear the list of child PresShells generated during the last paint
-   * so that we can begin generating a new one.
-   */
-  void ClearPresShellsFromLastPaint() { PaintedPresShellList()->Clear(); }
-
-  /**
-   * Flag a child PresShell as painted so that it will get its paint count
-   * incremented during empty transactions.
-   */
-  void AddPaintedPresShell(mozilla::PresShell* aPresShell);
-
-  /**
-   * Increment the paint count of all child PresShells that were painted during
-   * the last repaint.
-   */
-  void UpdatePaintCountForPaintedPresShells();
-
   /**
    * Accessors for the absolute containing block.
    */
@@ -4475,7 +4457,7 @@ class nsIFrame : public nsQueryFrame {
     return kAbsoluteList;
   }
 
-  // Checks if we (or any of our descendents) have NS_FRAME_PAINTED_THEBES set,
+  // Checks if we (or any of our descendants) have NS_FRAME_PAINTED_THEBES set,
   // and clears this bit if so.
   bool CheckAndClearPaintedState();
 
@@ -5010,27 +4992,6 @@ class nsIFrame : public nsQueryFrame {
 
   void MarkAbsoluteFramesForDisplayList(nsDisplayListBuilder* aBuilder);
 
-  // Stores weak references to all the PresShells that were painted during
-  // the last paint event so that we can increment their paint count during
-  // empty transactions
-  NS_DECLARE_FRAME_PROPERTY_DELETABLE(PaintedPresShellsProperty,
-                                      nsTArray<nsWeakPtr>)
-
-  nsTArray<nsWeakPtr>* PaintedPresShellList() {
-    bool found;
-    nsTArray<nsWeakPtr>* list =
-        GetProperty(PaintedPresShellsProperty(), &found);
-
-    if (!found) {
-      list = new nsTArray<nsWeakPtr>();
-      AddProperty(PaintedPresShellsProperty(), list);
-    } else {
-      MOZ_ASSERT(list, "this property should only store non-null values");
-    }
-
-    return list;
-  }
-
  protected:
   void MarkInReflow() {
 #ifdef DEBUG_dbaron_off

layout/painting/nsDisplayList.cpp

@@ -1056,7 +1056,6 @@ nsCaret* nsDisplayListBuilder::GetCaret() {
 
 void nsDisplayListBuilder::IncrementPresShellPaintCount(PresShell* aPresShell) {
   if (mIsPaintingToWindow) {
-    mReferenceFrame->AddPaintedPresShell(aPresShell);
     aPresShell->IncrementPaintCount();
   }
 }