Account for borders and padding when calculating background tile size.

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

Index: third_party/WebKit/Source/core/paint/BackgroundImageGeometry.cpp
diff --git a/third_party/WebKit/Source/core/paint/BackgroundImageGeometry.cpp b/third_party/WebKit/Source/core/paint/BackgroundImageGeometry.cpp
index b99d4c261c8fb26ceab93ca07985b2e888b63a83..8805210bc5144a2758e1c5536eef57f5a2f3b141 100644
--- a/third_party/WebKit/Source/core/paint/BackgroundImageGeometry.cpp
+++ b/third_party/WebKit/Source/core/paint/BackgroundImageGeometry.cpp
@@ -528,7 +528,7 @@ void BackgroundImageGeometry::calculate(
   // It's necessary to apply the heuristic here prior to any further
   // calculations to avoid incorrectly using sub-pixel values that won't be
   // present in the painted tile.
-  setTileSize(applySubPixelHeuristicToImageSize(fillTileSize, m_destRect));
+  setTileSize(applySubPixelHeuristicToImageSize(fillTileSize, positioningArea));
 
   EFillRepeat backgroundRepeatX = fillLayer.repeatX();
   EFillRepeat backgroundRepeatY = fillLayer.repeatY();
@@ -559,7 +559,8 @@ void BackgroundImageGeometry::calculate(
     }
     fillTileSize.setWidth(roundedWidth);
 
-    setTileSize(applySubPixelHeuristicToImageSize(fillTileSize, m_destRect));
+    setTileSize(
+        applySubPixelHeuristicToImageSize(fillTileSize, positioningArea));
     setPhaseX(tileSize().width()
                   ? LayoutUnit(roundf(
                         tileSize().width() -
@@ -585,7 +586,8 @@ void BackgroundImageGeometry::calculate(
     }
     fillTileSize.setHeight(roundedHeight);
 
-    setTileSize(applySubPixelHeuristicToImageSize(fillTileSize, m_destRect));
+    setTileSize(
+        applySubPixelHeuristicToImageSize(fillTileSize, positioningArea));
     setPhaseY(tileSize().height()
                   ? LayoutUnit(roundf(
                         tileSize().height() -