Round visual rects when crossing frame boundaries.

third_party/WebKit/Source/core/layout/PaintInvalidationState.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/layout/PaintInvalidationState.h"
 
 #include "core/frame/FrameView.h"
 #include "core/frame/Settings.h"
 #include "core/layout/LayoutInline.h"
 #include "core/layout/LayoutPart.h"
@@ skipping 135 matching lines @@
         m_paintOffset = LayoutSize();
         return;
     }
 
     if (!m_cachedOffsetsEnabled)
         return;
 
     if (currentObject.isLayoutView()) {
         ASSERT(&parentState.m_currentObject == toLayoutView(currentObject).frame()->ownerLayoutObject());
         m_paintOffset += toLayoutBox(parentState.m_currentObject).contentBoxOffset();
+        // a LayoutView paints with a defined size but a pixel-rounded offset.
+        m_paintOffset = LayoutSize(roundedIntSize(m_paintOffset));
         return;
     }
 
     if (currentObject.isBox())
         m_paintOffset += toLayoutBox(currentObject).locationOffset();
 
     if (currentObject.isInFlowPositioned() && currentObject.hasLayer())
         m_paintOffset += toLayoutBoxModelObject(currentObject).layer()->offsetForInFlowPosition();
 }
 
@@ skipping 178 matching lines @@
 
 PaintLayer& PaintInvalidationState::enclosingSelfPaintingLayer(const LayoutObject& layoutObject) const
 {
     if (layoutObject.hasLayer() && toLayoutBoxModelObject(layoutObject).hasSelfPaintingLayer())
         return *toLayoutBoxModelObject(layoutObject).layer();
 
     return m_enclosingSelfPaintingLayer;
 }
 
 } // namespace blink