Bug 1274528 - Don't enforce layers.max-active when layerizing items with different AGRs. r=mstange

This reverts bug 1231818, as it caused problems with async scrolling on
pages with too many active layers.

MozReview-Commit-ID: 8eGjn4fzWFb

layout/base/FrameLayerBuilder.cpp

@@ -954,7 +954,6 @@ public:
                                         const nsIntRect& aVisibleRect,
                                         bool aForceOwnLayer,
                                         bool aBackfaceidden,
-                                        bool aAvoidCreatingNewLayer,
                                         NewPaintedLayerCallbackType aNewPaintedLayerCallback);
 
   /**
@@ -1007,12 +1006,6 @@ protected:
    */
   PaintedLayerDataNode* EnsureNodeFor(AnimatedGeometryRoot* aAnimatedGeometryRoot);
 
-  /**
-   * Find the node for the nearest ancestor geometry root of
-   * aAnimatedGeometryRoot which already exists in the tree.
-   */
-  PaintedLayerDataNode* FindNodeForNearestAncestor(AnimatedGeometryRoot* aAnimatedGeometryRoot);
-
   /**
    * Find an existing node in the tree for an ancestor of aAnimatedGeometryRoot.
    * *aOutAncestorChild will be set to the last ancestor that was encountered
@@ -2824,18 +2817,11 @@ PaintedLayerDataTree::FindPaintedLayerFor(AnimatedGeometryRoot* aAnimatedGeometr
                                           const nsIntRect& aVisibleRect,
                                           bool aForceOwnLayer,
                                           bool aBackfaceHidden,
-                                          bool aAvoidCreatingNewLayer,
                                           NewPaintedLayerCallbackType aNewPaintedLayerCallback)
 {
   const nsIntRect* bounds = aForceOwnLayer ? nullptr : &aVisibleRect;
   FinishPotentiallyIntersectingNodes(aAnimatedGeometryRoot, bounds);
-  PaintedLayerDataNode* node = nullptr;
-  if (aAvoidCreatingNewLayer) {
-    node = FindNodeForNearestAncestor(aAnimatedGeometryRoot);
-  }
-  if (!node) {
-    node = EnsureNodeFor(aAnimatedGeometryRoot);
-  }
+  PaintedLayerDataNode* node = EnsureNodeFor(aAnimatedGeometryRoot);
 
   if (aForceOwnLayer) {
     node->SetAllDrawingAbove();
@@ -2920,21 +2906,6 @@ PaintedLayerDataTree::EnsureNodeFor(AnimatedGeometryRoot* aAnimatedGeometryRoot)
   return node;
 }
 
-PaintedLayerDataNode*
-PaintedLayerDataTree::FindNodeForNearestAncestor(AnimatedGeometryRoot* aAnimatedGeometryRoot)
-{
-  if (aAnimatedGeometryRoot) {
-    PaintedLayerDataNode* node = mNodes.Get(aAnimatedGeometryRoot);
-    if (node) {
-      return node;
-    }
-
-    return FindNodeForNearestAncestor(aAnimatedGeometryRoot->mParentAGR);
-  }
-
-  return nullptr;
-}
-
 bool
 PaintedLayerDataTree::IsClippedWithRespectToParentAnimatedGeometryRoot(AnimatedGeometryRoot* aAnimatedGeometryRoot,
                                                                        nsIntRect* aOutClip)
@@ -4216,14 +4187,11 @@ ContainerState::ProcessDisplayItems(nsDisplayList* aList)
        */
       mLayerBuilder->AddLayerDisplayItem(ownLayer, item, layerState, nullptr);
     } else {
-      bool avoidCreatingLayer = (maxLayers != -1 && layerCount >= maxLayers);
       PaintedLayerData* paintedLayerData =
         mPaintedLayerDataTree.FindPaintedLayerFor(animatedGeometryRoot, agrScrollClip,
                                                   itemVisibleRect, false,
                                                   item->Frame()->In3DContextAndBackfaceIsHidden(),
-                                                  avoidCreatingLayer,
                                                   [&]() {
-          layerCount++;
           return NewPaintedLayerData(item, animatedGeometryRoot, agrScrollClip,
                                      topLeft, clipMovesWithLayer);
         });