Tweaking how background images interact with sub pixel borders. *** NOT FOR LANDING

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 41c0b148ca7bd05287de48a2787909a569a2a56f..14ec0a3ee1b002fa1625233b2801dc8199caa147 100644
--- a/third_party/WebKit/Source/core/paint/BackgroundImageGeometry.cpp
+++ b/third_party/WebKit/Source/core/paint/BackgroundImageGeometry.cpp
@@ -467,15 +467,19 @@ void BackgroundImageGeometry::Calculate(
     LayoutUnit bottom;
     // Scroll and Local.
     if (fill_layer.Origin() != kBorderFillBox) {
-      left = LayoutUnit(positioning_box.BorderLeft());
-      right = LayoutUnit(positioning_box.BorderRight());
-      top = LayoutUnit(positioning_box.BorderTop());
-      bottom = LayoutUnit(positioning_box.BorderBottom());
+      left = LayoutUnit(positioning_box.BorderLeft().Round());
+      right = LayoutUnit(positioning_box.BorderRight().Round());
+      top = LayoutUnit(positioning_box.BorderTop().Round());
+      bottom = LayoutUnit(positioning_box.BorderBottom().Round());
       if (fill_layer.Origin() == kContentFillBox) {
-        left += positioning_box.PaddingLeft();
-        right += positioning_box.PaddingRight();
-        top += positioning_box.PaddingTop();
-        bottom += positioning_box.PaddingBottom();
+        left = std::max(
+            left, positioning_box.BorderLeft() + positioning_box.PaddingLeft());
+        right = std::max(right, positioning_box.BorderRight() +
+                                    positioning_box.PaddingRight());
+        top = std::max(
+            top, positioning_box.BorderTop() + positioning_box.PaddingTop());
+        bottom = std::max(bottom, positioning_box.BorderBottom() +
+                                      positioning_box.PaddingBottom());
       }
     }
 
@@ -604,7 +608,9 @@ void BackgroundImageGeometry::Calculate(
 
   if (background_repeat_x == kRepeatFill) {
     SetRepeatX(fill_layer, fill_tile_size.Width(), available_width,
-               unsnapped_available_width, left, offset_in_background.X());
+               unsnapped_available_width,
+               LayoutUnit(SnapSizeToPixel(left, dest_rect_.X())),
+               offset_in_background.X());
   } else if (background_repeat_x == kSpaceFill &&
              TileSize().Width() > LayoutUnit()) {
     LayoutUnit space = GetSpaceBetweenImageTiles(positioning_area_size.Width(),
@@ -625,7 +631,9 @@ void BackgroundImageGeometry::Calculate(
 
   if (background_repeat_y == kRepeatFill) {
     SetRepeatY(fill_layer, fill_tile_size.Height(), available_height,
-               unsnapped_available_height, top, offset_in_background.Y());
+               unsnapped_available_height,
+               LayoutUnit(SnapSizeToPixel(top, dest_rect_.Y())),
+               offset_in_background.Y());
   } else if (background_repeat_y == kSpaceFill &&
              TileSize().Height() > LayoutUnit()) {
     LayoutUnit space = GetSpaceBetweenImageTiles(positioning_area_size.Height(),