Keep a cache of caret painters to avoid recomputing all the time.

Source/core/paint/DeprecatedPaintLayerPaintingInfo.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. 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 34 matching lines @@
 #ifndef DeprecatedPaintLayerPaintingInfo_h
 #define DeprecatedPaintLayerPaintingInfo_h
 
 #include "core/paint/PaintPhase.h"
 #include "platform/geometry/LayoutRect.h"
 
 namespace blink {
 
 class DeprecatedPaintLayer;
 class LayoutObject;
+class PaintDataCache;
 
 enum PaintLayerFlag {
     PaintLayerHaveTransparency = 1,
     PaintLayerAppliedTransform = 1 << 1,
     PaintLayerUncachedClipRects = 1 << 2,
     PaintLayerPaintingReflection = 1 << 3,
     PaintLayerPaintingOverlayScrollbars = 1 << 4,
     PaintLayerPaintingCompositingBackgroundPhase = 1 << 5,
     PaintLayerPaintingCompositingForegroundPhase = 1 << 6,
     PaintLayerPaintingCompositingMaskPhase = 1 << 7,
     PaintLayerPaintingCompositingScrollingPhase = 1 << 8,
     PaintLayerPaintingOverflowContents = 1 << 9,
     PaintLayerPaintingRootBackgroundOnly = 1 << 10,
     PaintLayerPaintingSkipRootBackground = 1 << 11,
     PaintLayerPaintingChildClippingMaskPhase = 1 << 12,
     PaintLayerPaintingCompositingAllPhases = (PaintLayerPaintingCompositingBackgroundPhase | PaintLayerPaintingCompositingForegroundPhase | PaintLayerPaintingCompositingMaskPhase)
 };
 
 typedef unsigned PaintLayerFlags;
 
 struct DeprecatedPaintLayerPaintingInfo {
     DeprecatedPaintLayerPaintingInfo(DeprecatedPaintLayer* inRootLayer, const LayoutRect& inDirtyRect,
         PaintBehavior inPaintBehavior, const LayoutSize& inSubPixelAccumulation,
-        LayoutObject* inPaintingRoot = 0)
+        LayoutObject* inPaintingRoot = 0, PaintDataCache* inPaintDataCache = nullptr)
         : rootLayer(inRootLayer)
         , paintingRoot(inPaintingRoot)
         , paintDirtyRect(inDirtyRect)
         , subPixelAccumulation(inSubPixelAccumulation)
         , paintBehavior(inPaintBehavior)
         , clipToDirtyRect(true)
+        , paintDataCache(inPaintDataCache)
     { }
     DeprecatedPaintLayer* rootLayer;
     LayoutObject* paintingRoot; // only paint descendants of this object
     LayoutRect paintDirtyRect; // relative to rootLayer;
     LayoutSize subPixelAccumulation;
     IntSize scrollOffsetAccumulation;
     PaintBehavior paintBehavior;
     bool clipToDirtyRect;
+    PaintDataCache* paintDataCache;
 };
 
 } // namespace blink
 
 #endif // DeprecatedPaintLayerPaintingInfo_h