Add API to view manager to get/set default background color (used when refresh disabled and possibly useful for other things). Have Docshell preserve background color across page loads. Make root frames set background color. Fix for bug 75591. r=waterson,sr=attinasi,a=blizzard

git-svn-id: svn://10.0.0.236/trunk@92978 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/layout/generic/nsHTMLFrame.cpp

@@ -85,6 +85,11 @@ public:
     return NS_OK;
   }
 
+  NS_IMETHOD Paint(nsIPresContext* aPresContext,
+                   nsIRenderingContext& aRenderingContext,
+                   const nsRect& aDirtyRect,
+                   nsFramePaintLayer aWhichLayer);
+
   /**
    * Get the "type" of the frame
    *
@@ -220,6 +225,18 @@ CanvasFrame::RemoveFrame(nsIPresContext* aPresContext,
   return rv;
 }
 
+NS_IMETHODIMP
+CanvasFrame::Paint(nsIPresContext* aPresContext,
+                   nsIRenderingContext& aRenderingContext,
+                   const nsRect& aDirtyRect,
+                   nsFramePaintLayer aWhichLayer)
+{
+  if (NS_FRAME_PAINT_LAYER_BACKGROUND == aWhichLayer) {
+    SetDefaultBackgroundColor(aPresContext);
+  }
+  return nsHTMLContainerFrame::Paint(aPresContext, aRenderingContext, aDirtyRect, aWhichLayer);
+}
+
 NS_IMETHODIMP
 CanvasFrame::Reflow(nsIPresContext*          aPresContext,
                     nsHTMLReflowMetrics&     aDesiredSize,