Make PaintLayerClipper objects transient

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

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/PaintLayerPainter.h"
 
 #include "core/frame/FrameView.h"
 #include "core/frame/Settings.h"
 #include "core/layout/ClipPathOperation.h"
 #include "core/layout/LayoutBlock.h"
@@ skipping 205 matching lines @@
 
 static bool shouldRepaintSubsequence(PaintLayer& paintLayer, const PaintLayerPaintingInfo& paintingInfo, ShouldRespectOverflowClip respectOverflowClip, const LayoutSize& subpixelAccumulation)
 {
     bool needsRepaint = false;
 
     // Repaint subsequence if the layer is marked for needing repaint.
     if (paintLayer.needsRepaint())
         needsRepaint = true;
 
     // Repaint if layer's clip changes.
-    ClipRects* clipRects = paintLayer.clipper().paintingClipRects(paintingInfo.rootLayer, respectOverflowClip, subpixelAccumulation);
+    ClipRects& clipRects = paintLayer.clipper().paintingClipRects(paintingInfo.rootLayer, respectOverflowClip, subpixelAccumulation);
     ClipRects* previousClipRects = paintLayer.previousPaintingClipRects();
-    if (!needsRepaint && clipRects != previousClipRects && (!clipRects || !previousClipRects || *clipRects != *previousClipRects))
+    if (!needsRepaint && &clipRects != previousClipRects && (!previousClipRects || clipRects != *previousClipRects))
         needsRepaint = true;
     paintLayer.setPreviousPaintingClipRects(clipRects);
 
     // Repaint if previously the layer might be clipped by paintDirtyRect and paintDirtyRect changes.
     if (!needsRepaint && paintLayer.previousPaintResult() == PaintLayerPainter::MayBeClippedByPaintDirtyRect && paintLayer.previousPaintDirtyRect() != paintingInfo.paintDirtyRect)
         needsRepaint = true;
     paintLayer.setPreviousPaintDirtyRect(paintingInfo.paintDirtyRect);
 
     // Repaint if scroll offset accumulation changes.
     if (!needsRepaint && paintingInfo.scrollOffsetAccumulation != paintLayer.previousScrollOffsetAccumulationForPainting())
@@ skipping 497 matching lines @@
     if (!m_paintLayer.containsDirtyOverlayScrollbars())
         return;
 
     PaintLayerPaintingInfo paintingInfo(&m_paintLayer, LayoutRect(enclosingIntRect(damageRect)), paintFlags, LayoutSize());
     paintLayer(context, paintingInfo, PaintLayerPaintingOverlayScrollbars);
 
     m_paintLayer.setContainsDirtyOverlayScrollbars(false);
 }
 
 } // namespace blink