Bug 505184. Expose nsFrame::DisplayBackgroundUnconditional so we can easily create an nsDisplayBackground elsewhere. r=dbaron

layout/generic/nsFrame.cpp

@@ -960,6 +960,22 @@ nsFrame::HasBorder() const
           GetStyleBorder()->IsBorderImageLoaded());
 }
 
+nsresult
+nsFrame::DisplayBackgroundUnconditional(nsDisplayListBuilder*   aBuilder,
+                                        const nsDisplayListSet& aLists,
+                                        PRBool                  aForceBackground)
+{
+  // Here we don't try to detect background propagation. Frames that might
+  // receive a propagated background should just set aForceBackground to
+  // PR_TRUE.
+  if (aBuilder->IsForEventDelivery() || aForceBackground ||
+      !GetStyleBackground()->IsTransparent() || GetStyleDisplay()->mAppearance) {
+    return aLists.BorderBackground()->AppendNewToTop(new (aBuilder)
+        nsDisplayBackground(this));
+  }
+  return NS_OK;
+}
+
 nsresult
 nsFrame::DisplayBorderBackgroundOutline(nsDisplayListBuilder*   aBuilder,
                                         const nsDisplayListSet& aLists,
@@ -978,24 +994,18 @@ nsFrame::DisplayBorderBackgroundOutline(nsDisplayListBuilder*   aBuilder,
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
-  // Here we don't try to detect background propagation. Frames that might
-  // receive a propagated background should just set aForceBackground to
-  // PR_TRUE.
-  if (aBuilder->IsForEventDelivery() || aForceBackground ||
-      !GetStyleBackground()->IsTransparent() || GetStyleDisplay()->mAppearance) {
-    nsresult rv = aLists.BorderBackground()->AppendNewToTop(new (aBuilder)
-        nsDisplayBackground(this));
-    NS_ENSURE_SUCCESS(rv, rv);
-  }
+  nsresult rv =
+    DisplayBackgroundUnconditional(aBuilder, aLists, aForceBackground);
+  NS_ENSURE_SUCCESS(rv, rv);
 
   if (hasBoxShadow) {
-    nsresult rv = aLists.BorderBackground()->AppendNewToTop(new (aBuilder)
+    rv = aLists.BorderBackground()->AppendNewToTop(new (aBuilder)
         nsDisplayBoxShadowInner(this));
     NS_ENSURE_SUCCESS(rv, rv);
   }
   
   if (HasBorder()) {
-    nsresult rv = aLists.BorderBackground()->AppendNewToTop(new (aBuilder)
+    rv = aLists.BorderBackground()->AppendNewToTop(new (aBuilder)
         nsDisplayBorder(this));
     NS_ENSURE_SUCCESS(rv, rv);
   }

layout/generic/nsFrame.h

@@ -497,6 +497,17 @@ public:
   static void DisplayReflowShutdown();
 #endif
 
+  /**
+   * Adds display item for standard CSS background if necessary.
+   * Does not check IsVisibleForPainting.
+   * @param aForceBackground draw the background even if the frame
+   * background style appears to have no background --- this is useful
+   * for frames that might receive a propagated background via
+   * nsCSSRendering::FindBackground
+   */
+  nsresult DisplayBackgroundUnconditional(nsDisplayListBuilder*   aBuilder,
+                                          const nsDisplayListSet& aLists,
+                                          PRBool aForceBackground = PR_FALSE);
   /**
    * Adds display items for standard CSS borders, background and outline for
    * for this frame, as necessary. Checks IsVisibleForPainting and won't