Adjust for viewport scrollbars when positioning a fixed background. b=402807 r+sr=roc a=blocking1.9

layout/base/nsCSSRendering.cpp

@@ -3591,8 +3591,9 @@ nsCSSRendering::PaintBackgroundWithSC(nsPresContext* aPresContext,
     nsIFrame* topFrame =
       aPresContext->PresShell()->FrameManager()->GetRootFrame();
     NS_ASSERTION(topFrame, "no root frame");
+    nsIFrame* pageContentFrame = nsnull;
     if (aPresContext->IsPaginated()) {
-      nsIFrame* pageContentFrame =
+      pageContentFrame =
         nsLayoutUtils::GetClosestFrameOfType(aForFrame, nsGkAtoms::pageContentFrame);
       if (pageContentFrame) {
         topFrame = pageContentFrame;
@@ -3600,8 +3601,19 @@ nsCSSRendering::PaintBackgroundWithSC(nsPresContext* aPresContext,
       // else this is an embedded shell and its root frame is what we want
     }
 
-    // Get the anchor point, relative to the viewport.
     nsRect viewportArea = topFrame->GetRect();
+
+    if (!pageContentFrame) {
+      // Subtract the size of scrollbars.
+      nsIScrollableFrame* scrollableFrame =
+        aPresContext->PresShell()->GetRootScrollFrameAsScrollable();
+      if (scrollableFrame) {
+        nsMargin scrollbars = scrollableFrame->GetActualScrollbarSizes();
+        viewportArea.Deflate(scrollbars);
+      }
+    }
+     
+    // Get the anchor point, relative to the viewport.
     ComputeBackgroundAnchorPoint(aColor, viewportArea, viewportArea, tileWidth, tileHeight, anchor);
 
     // Convert the anchor point from viewport coordinates to aForFrame

layout/reftests/bugs/reftest.list

@@ -618,7 +618,7 @@ skip-if(MOZ_WIDGET_TOOLKIT!="windows") == 391045.html 391045-ref.html # windows-
 == 402567-2.html 402567-2-ref.html
 == 402567-3.html 402567-3-ref.html
 == 402567-4.html 402567-4-ref.html
-fails == 402807-1.html 402807-1-ref.html # bug 402807
+== 402807-1.html 402807-1-ref.html
 == 402950-1.html 402950-1-ref.html
 == 403129-1.html 403129-1-ref.html
 == 403129-2.html 403129-2-ref.html