Remove unused variable from UpdatePaintingLayer().

Change-Id: Ibe62dcbc3f17bf175186a5e67925da2c2cf8d145
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2072180Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#744301}

third_party/blink/renderer/core/paint/paint_property_tree_builder.cc

@@ -3291,17 +3291,14 @@ bool PaintPropertyTreeBuilder::ObjectTypeMightNeedMultipleFragmentData() const {
 }
 
 void PaintPropertyTreeBuilder::UpdatePaintingLayer() {
-  bool changed_painting_layer = false;
   if (object_.HasLayer() &&
       ToLayoutBoxModelObject(object_).HasSelfPaintingLayer()) {
     context_.painting_layer = ToLayoutBoxModelObject(object_).Layer();
-    changed_painting_layer = true;
   } else if (object_.IsColumnSpanAll() ||
              object_.IsFloatingWithNonContainingBlockParent()) {
     // See LayoutObject::paintingLayer() for the special-cases of floating under
     // inline and multicolumn.
     context_.painting_layer = object_.PaintingLayer();
-    changed_painting_layer = true;
   }
   DCHECK(context_.painting_layer == object_.PaintingLayer());
 }