Allow for paint offset roots that don't have PaintLayers.

LayoutSVGRoot is not always a stacking context at present,
so it does not always have a PaintLayer.

TBR=chrishtr@chromium.org

(cherry picked from commit 68c4cdb)

Bug: 773198
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: Ia146f3a90512b98de961bd1f243b9e8439c6d382
Reviewed-on: https://chromium-review.googlesource.com/717564
Reviewed-by: Tien-Ren Chen <trchen@chromium.org>
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#508817}
Reviewed-on: https://chromium-review.googlesource.com/719586
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/branch-heads/3239@{#8}
Cr-Branched-From: adb61db-refs/heads/master@{#508578}

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp

@@ -163,7 +163,7 @@ void PaintPropertyTreeBuilder::UpdateProperties(
     context.fixed_position.fixed_position_children_fixed_to_root = true;
     return;
   } else {
-    context.current.paint_offset_root = frame_view.GetLayoutView()->Layer();
+    context.current.paint_offset_root = frame_view.GetLayoutView();
   }
 
 #if DCHECK_IS_ON()
@@ -1269,7 +1269,7 @@ void PaintPropertyTreeBuilder::UpdatePaintOffset(
       // above the scroll of the LayoutView. Child content is relative to that
       // transform, and hence the fixed-position element.
       if (context.fixed_position.fixed_position_children_fixed_to_root)
-        context.current.paint_offset_root = object.Layer();
+        context.current.paint_offset_root = &object;
       break;
     default:
       NOTREACHED();
@@ -1296,13 +1296,19 @@ void PaintPropertyTreeBuilder::UpdatePaintOffset(
 static inline LayoutPoint VisualOffsetFromPaintOffsetRoot(
     const PaintPropertyTreeBuilderFragmentContext& context,
     const PaintLayer* child) {
-  PaintLayer* paint_offset_root = context.current.paint_offset_root;
-  LayoutPoint result = child->VisualOffsetFromAncestor(paint_offset_root);
+  const LayoutBoxModelObject* paint_offset_root =
+      context.current.paint_offset_root;
+  PaintLayer* painting_layer = paint_offset_root->PaintingLayer();
+  LayoutPoint result = child->VisualOffsetFromAncestor(painting_layer);
+  if (!paint_offset_root->Layer()) {
+    result.Move(-paint_offset_root->OffsetFromAncestorContainer(
+        &painting_layer->GetLayoutObject()));
+  }
 
   // Don't include scroll offset of paint_offset_root. Any scroll is
   // already included in a separate transform node.
-  if (paint_offset_root->GetLayoutObject().HasOverflowClip())
-    result += paint_offset_root->GetLayoutBox()->ScrolledContentOffset();
+  if (paint_offset_root->HasOverflowClip())
+    result += ToLayoutBox(paint_offset_root)->ScrolledContentOffset();
   return result;
 }
 
@@ -1351,8 +1357,7 @@ void PaintPropertyTreeBuilder::UpdateForObjectLocationAndSize(
     paint_offset.MoveBy(
         VisualOffsetFromPaintOffsetRoot(context, enclosing_pagination_layer));
     // The paint offset root can have a subpixel paint offset adjustment.
-    paint_offset.MoveBy(
-        context.current.paint_offset_root->GetLayoutObject().PaintOffset());
+    paint_offset.MoveBy(context.current.paint_offset_root->PaintOffset());
 
     if (paint_offset_translation) {
       paint_offset_translation =
@@ -1364,7 +1369,7 @@ void PaintPropertyTreeBuilder::UpdateForObjectLocationAndSize(
   }
 
   if (paint_offset_translation)
-    context.current.paint_offset_root = ToLayoutBoxModelObject(object).Layer();
+    context.current.paint_offset_root = &ToLayoutBoxModelObject(object);
 
   if (!object.IsBox())
     return;
@@ -1525,8 +1530,7 @@ void PaintPropertyTreeBuilder::UpdateFragments(
           // component.
           pagination_visual_offset.MoveBy(
               full_context.fragments[0]
-                  .current.paint_offset_root->GetLayoutObject()
-                  .PaintOffset());
+                  .current.paint_offset_root->PaintOffset());
 
           fragment_clip.MoveBy(pagination_visual_offset);
         }

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.h

@@ -50,7 +50,7 @@ struct PaintPropertyTreeBuilderFragmentContext {
     // fragmentation offsets. See FragmentContext for the fragmented version.
     LayoutPoint paint_offset;
     // The PaintLayer corresponding to the origin of |paint_offset|.
-    PaintLayer* paint_offset_root = nullptr;
+    const LayoutBoxModelObject* paint_offset_root = nullptr;
     // Whether newly created children should flatten their inherited transform
     // (equivalently, draw into the plane of their parent). Should generally
     // be updated whenever |transform| is; flattening only needs to happen

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilderTest.cpp

@@ -1130,6 +1130,62 @@ TEST_P(PaintPropertyTreeBuilderTest, TransformNodesAcrossSVGHTMLBoundary) {
             div_with_transform_properties->Transform()->Parent());
 }
 
+TEST_P(PaintPropertyTreeBuilderTest, PaintOffsetTranslationSVGHTMLBoundary) {
+  SetBodyInnerHTML(
+      "<svg id='svg'"
+      "  <foreignObject>"
+      "    <body>"
+      "      <div id='divWithTransform'"
+      "          style='transform: translate3d(3px, 4px, 5px);'></div>"
+      "    </body>"
+      "  </foreignObject>"
+      "</svg>");
+
+  LayoutObject& svg = *GetLayoutObjectByElementId("svg");
+  const ObjectPaintProperties* svg_properties =
+      svg.FirstFragment()->PaintProperties();
+  EXPECT_EQ(
+      FloatSize(8, 8),
+      svg_properties->PaintOffsetTranslation()->Matrix().To2DTranslation());
+
+  LayoutObject& div_with_transform =
+      *GetLayoutObjectByElementId("divWithTransform");
+  const ObjectPaintProperties* div_with_transform_properties =
+      div_with_transform.FirstFragment()->PaintProperties();
+  EXPECT_EQ(TransformationMatrix().Translate3d(3, 4, 5),
+            div_with_transform_properties->Transform()->Matrix());
+  EXPECT_EQ(FloatSize(8, 158),
+            div_with_transform_properties->PaintOffsetTranslation()
+                ->Matrix()
+                .To2DTranslation());
+  EXPECT_EQ(div_with_transform_properties->PaintOffsetTranslation(),
+            div_with_transform_properties->Transform()->Parent());
+}
+
+TEST_P(PaintPropertyTreeBuilderTest,
+       PaintOffsetTranslationSVGHTMLBoundaryMulticol) {
+  SetBodyInnerHTML(
+      "<svg id='svg'>"
+      "  <foreignObject>"
+      "    <body>"
+      "      <div id='divWithColumns' style='columns: 2'>"
+      "        <div style='width: 5px; height: 5px; background: blue'>"
+      "      </div>"
+      "    </body>"
+      "  </foreignObject>"
+      "</svg>");
+
+  LayoutObject& svg = *GetLayoutObjectByElementId("svg");
+  const ObjectPaintProperties* svg_properties =
+      svg.FirstFragment()->PaintProperties();
+  EXPECT_EQ(
+      FloatSize(8, 8),
+      svg_properties->PaintOffsetTranslation()->Matrix().To2DTranslation());
+  LayoutObject& div_with_columns =
+      *GetLayoutObjectByElementId("divWithColumns")->SlowFirstChild();
+  EXPECT_EQ(LayoutPoint(0, 0), div_with_columns.FirstFragment()->PaintOffset());
+}
+
 TEST_P(PaintPropertyTreeBuilderTest,
        FixedTransformAncestorAcrossSVGHTMLBoundary) {
   SetBodyInnerHTML(