Move all ancestor-dependent properties out of PaintLayer and into an aux. struct.

third_party/WebKit/Source/core/paint/PaintLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights
  * reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
@@ skipping 83 matching lines @@
 
 namespace blink {
 
 namespace {
 
 static CompositingQueryMode gCompositingQueryMode =
     CompositingQueriesAreOnlyAllowedInCertainDocumentLifecyclePhases;
 
 struct SameSizeAsPaintLayer : DisplayItemClient {
   int bitFields;
-  void* pointers[10];

[chrishtr, 2016/11/08 00:48:42]

This was wrong before.

+  void* pointers[11];
   LayoutUnit layoutUnits[4];
   IntSize size;
   Persistent<PaintLayerScrollableArea> scrollableArea;
   struct {
-    IntRect rect, rect2;
-    void* pointers[2];
-  } ancestorCompositingInputs;
-  struct {
     IntSize size;
     void* pointer;
     LayoutRect rect;
   } previousPaintStatus;
 };
 
 static_assert(sizeof(PaintLayer) == sizeof(SameSizeAsPaintLayer),
               "PaintLayer should stay small");
 
 }  // namespace
@@ skipping 895 matching lines @@
        current && !current->m_childNeedsCompositingInputsUpdate;
        current = current->parent())
     current->m_childNeedsCompositingInputsUpdate = true;
 
   compositor()->setNeedsCompositingUpdate(
       CompositingUpdateAfterCompositingInputChange);
 }
 
 void PaintLayer::updateAncestorDependentCompositingInputs(
     const AncestorDependentCompositingInputs& compositingInputs,
-    const RareAncestorDependentCompositingInputs& rareCompositingInputs,
     bool hasAncestorWithClipPath) {
-  m_ancestorDependentCompositingInputs = compositingInputs;
-  if (rareCompositingInputs.isDefault())
-    m_rareAncestorDependentCompositingInputs.reset();
-  else
-    m_rareAncestorDependentCompositingInputs = wrapUnique(
-        new RareAncestorDependentCompositingInputs(rareCompositingInputs));
+  m_ancestorDependentCompositingInputs =
+      wrapUnique(new AncestorDependentCompositingInputs(compositingInputs));
   m_hasAncestorWithClipPath = hasAncestorWithClipPath;
   m_needsAncestorDependentCompositingInputsUpdate = false;
 }
 
 void PaintLayer::updateDescendantDependentCompositingInputs(
     bool hasDescendantWithClipPath,
     bool hasNonIsolatedDescendantWithBlendMode,
     bool hasRootScrollerAsDescendant) {
   m_hasDescendantWithClipPath = hasDescendantWithClipPath;
   m_hasNonIsolatedDescendantWithBlendMode =
@@ skipping 2228 matching lines @@
 }
 
 void showLayerTree(const blink::LayoutObject* layoutObject) {
   if (!layoutObject) {
     fprintf(stderr, "Cannot showLayerTree. Root is (nil)\n");
     return;
   }
   showLayerTree(layoutObject->enclosingLayer());
 }
 #endif