Implement a paint offset cache for slimming paint v2

Source/core/paint/ViewPainter.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 "config.h"
 #include "core/paint/ViewPainter.h"
 
 #include "core/frame/FrameView.h"
 #include "core/frame/Settings.h"
 #include "core/layout/LayoutBox.h"
@@ skipping 31 matching lines @@
     // 1. The view paints background for the root element, the background positioning respects
     //    the positioning and transformation of the root element.
     // 2. CSS background-clip is ignored, the background layers always expand to cover the whole
     //    canvas. None of the stacking context effects (except transformation) on the root element
     //    affects the background.
     // 3. The main frame is also responsible for painting the user-agent-defined base background
     //    color. Conceptually it should be painted by the embedder but painting it here allows
     //    culling and pre-blending optimization when possible.
 
     GraphicsContext& context = *paintInfo.context;
-    if (LayoutObjectDrawingRecorder::useCachedDrawingIfPossible(context, m_layoutView, DisplayItem::BoxDecorationBackground))
+    if (LayoutObjectDrawingRecorder::useCachedDrawingIfPossible(context, m_layoutView, DisplayItem::BoxDecorationBackground, LayoutPoint()))
         return;
 
     IntRect documentRect = m_layoutView.unscaledDocumentRect();
     const Document& document = m_layoutView.document();
     const FrameView& frameView = *m_layoutView.frameView();
     bool isMainFrame = !document.ownerElement();
     bool paintsBaseBackground = isMainFrame && !frameView.isTransparent();
     bool shouldClearCanvas = paintsBaseBackground && (document.settings() && document.settings()->shouldClearDocumentBackground());
     Color baseBackgroundColor = paintsBaseBackground ? frameView.baseBackgroundColor() : Color();
     Color rootBackgroundColor = m_layoutView.style()->visitedDependentColor(CSSPropertyBackgroundColor);
     const LayoutObject* rootObject = document.documentElement() ? document.documentElement()->layoutObject() : nullptr;
 
-    LayoutObjectDrawingRecorder recorder(context, m_layoutView, DisplayItem::BoxDecorationBackground, documentRect);
+    LayoutObjectDrawingRecorder recorder(context, m_layoutView, DisplayItem::BoxDecorationBackground, documentRect, LayoutPoint());
 
     // Special handling for print economy mode.
     bool forceBackgroundToWhite = BoxPainter::shouldForceWhiteBackgroundForPrintEconomy(m_layoutView.styleRef(), document);
     if (forceBackgroundToWhite) {
         // If for any reason the view background is not transparent, paint white instead, otherwise keep transparent as is.
         if (paintsBaseBackground || rootBackgroundColor.alpha() || m_layoutView.style()->backgroundLayers().image())
             context.fillRect(documentRect, Color::white, SkXfermode::kSrc_Mode);
         return;
     }
 
@@ skipping 65 matching lines @@
         ASSERT((*it)->clip() == BorderFillBox);
         BoxPainter::paintFillLayerExtended(m_layoutView, paintInfo, Color(), **it, LayoutRect(paintRect), BackgroundBleedNone);
     }
     context.restore();
 
     if (shouldDrawBackgroundInSeparateBuffer)
         context.endLayer();
 }
 
 } // namespace blink