Backed out changeset ce5bb779d929 (bug 1769953) for causing webrender…

… failures in overflow-top-left.html CLOSED TREE

gfx/wr/webrender_api/src/display_item.rs

@@ -42,18 +42,20 @@ bitflags! {
         const IS_BACKFACE_VISIBLE = 1 << 0;
         /// If set, this primitive represents a scroll bar container
         const IS_SCROLLBAR_CONTAINER = 1 << 1;
+        /// If set, this primitive represents a scroll bar thumb
+        const IS_SCROLLBAR_THUMB = 1 << 2;
         /// This is used as a performance hint - this primitive may be promoted to a native
         /// compositor surface under certain (implementation specific) conditions. This
         /// is typically used for large videos, and canvas elements.
-        const PREFER_COMPOSITOR_SURFACE = 1 << 2;
+        const PREFER_COMPOSITOR_SURFACE = 1 << 3;
         /// If set, this primitive can be passed directly to the compositor via its
         /// ExternalImageId, and the compositor will use the native image directly.
         /// Used as a further extension on top of PREFER_COMPOSITOR_SURFACE.
-        const SUPPORTS_EXTERNAL_COMPOSITOR_SURFACE = 1 << 3;
+        const SUPPORTS_EXTERNAL_COMPOSITOR_SURFACE = 1 << 4;
         /// This flags disables snapping and forces anti-aliasing even if the primitive is axis-aligned.
-        const ANTIALISED = 1 << 4;
+        const ANTIALISED = 1 << 5;
         /// If true, this primitive is used as a background for checkerboarding
-        const CHECKERBOARD_BACKGROUND = 1 << 5;
+        const CHECKERBOARD_BACKGROUND = 1 << 6;
     }
 }
 

layout/painting/nsDisplayList.cpp

@@ -5254,9 +5254,12 @@ bool nsDisplayOwnLayer::CreateWebRenderCommands(
   params.animation = prop.ptrOr(nullptr);
   params.clip =
       wr::WrStackingContextClip::ClipChain(aBuilder.CurrentClipChainId());
-  if (IsScrollbarContainer() && IsRootScrollbarContainer()) {
+  if (IsScrollbarContainer()) {
     params.prim_flags |= wr::PrimitiveFlags::IS_SCROLLBAR_CONTAINER;
   }
+  if (IsScrollThumbLayer()) {
+    params.prim_flags |= wr::PrimitiveFlags::IS_SCROLLBAR_THUMB;
+  }
   if (IsZoomingLayer() ||
       ((IsFixedPositionLayer() && HasDynamicToolbar()) ||
        (IsStickyPositionLayer() && HasDynamicToolbar()) ||