Introduce PaintPropertyTreeBuilderFragmentContext and use it throughout.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/PrePaintTreeWalk.h"
 
 #include "core/dom/DocumentLifecycle.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/layout/LayoutMultiColumnSpannerPlaceholder.h"
@@ skipping 111 matching lines @@
     // TODO(flackr): This should be refactored in the future to be clearer (i.e.
     // update layer position and ancestor inputs updates in the same walk).
     paint_layer->UpdateLayerPosition();
   }
 
   if (paint_layer->IsRootLayer() || object.HasOverflowClip())
     context.ancestor_overflow_paint_layer = paint_layer;
 }
 
 LayoutRect PrePaintTreeWalk::ComputeClipRectForContext(
-    const PaintPropertyTreeBuilderContext::ContainingBlockContext& context,
+    const PaintPropertyTreeBuilderFragmentContext::ContainingBlockContext&
+        context,
     const EffectPaintPropertyNode* effect,
     const PropertyTreeState& ancestor_state,
     const LayoutPoint& ancestor_paint_offset) {
   PropertyTreeState local_state(context.transform, context.clip, effect);
 
   const auto& clip_rect =
       GeometryMapper::SourceToDestinationClipRect(local_state, ancestor_state);
   // HasRadius() is ignored because it doesn't affect descendants' visual rects.
   LayoutRect result(clip_rect.Rect());
   if (!clip_rect.IsInfinite())
@@ skipping 44 matching lines @@
   const auto& old_clip_rects =
       paint_layer.Clipper(PaintLayer::kDoNotUseGeometryMapper)
           .PaintingClipRects(context.ancestor_transformed_or_root_paint_layer,
                              respect_overflow_clip, LayoutSize());
 #endif
 
   const LayoutPoint& ancestor_paint_offset =
       context.ancestor_transformed_or_root_paint_layer->GetLayoutObject()
           .PaintOffset();
 
-  const auto* effect = context.tree_builder_context->current_effect;
-  auto overflow_clip_rect =
-      ComputeClipRectForContext(context.tree_builder_context->current, effect,
-                                ancestor_state, ancestor_paint_offset);
+  // TODO(chrishtr): generalize this for multicol.
+  const auto* effect =
+      context.tree_builder_context->fragments[0].current_effect;
+  auto overflow_clip_rect = ComputeClipRectForContext(
+      context.tree_builder_context->fragments[0].current, effect,
+      ancestor_state, ancestor_paint_offset);
 #ifdef CHECK_CLIP_RECTS
   CHECK(overflow_clip_rect == old_clip_rects.OverflowClipRect().Rect())
       << " new=" << overflow_clip_rect.ToString()
       << " old=" << old_clip_rects.OverflowClipRect().Rect().ToString();
 #endif
 
-  auto fixed_clip_rect =
-      ComputeClipRectForContext(context.tree_builder_context->fixed_position,
-                                effect, ancestor_state, ancestor_paint_offset);
+  auto fixed_clip_rect = ComputeClipRectForContext(
+      context.tree_builder_context->fragments[0].fixed_position, effect,
+      ancestor_state, ancestor_paint_offset);
 #ifdef CHECK_CLIP_RECTS
   CHECK(fixed_clip_rect == old_clip_rects.FixedClipRect().Rect())
       << " new=" << fixed_clip_rect.ToString()
       << " old=" << old_clip_rects.FixedClipRect().Rect().ToString();
 #endif
 
-  auto pos_clip_rect =
-      ComputeClipRectForContext(context.tree_builder_context->absolute_position,
-                                effect, ancestor_state, ancestor_paint_offset);
+  auto pos_clip_rect = ComputeClipRectForContext(
+      context.tree_builder_context->fragments[0].absolute_position, effect,
+      ancestor_state, ancestor_paint_offset);
 #ifdef CHECK_CLIP_RECTS
   CHECK(pos_clip_rect == old_clip_rects.PosClipRect().Rect())
       << " new=" << pos_clip_rect.ToString()
       << " old=" << old_clip_rects.PosClipRect().Rect().ToString();
 #endif
 
   const auto* previous_clip_rects = paint_layer.PreviousPaintingClipRects();
   if (!previous_clip_rects ||
       overflow_clip_rect != previous_clip_rects->OverflowClipRect().Rect() ||
       fixed_clip_rect != previous_clip_rects->FixedClipRect().Rect() ||
@@ skipping 73 matching lines @@
       continue;
     }
     Walk(*child, context);
   }
 
   if (object.IsLayoutPart()) {
     const LayoutPart& layout_part = ToLayoutPart(object);
     FrameView* frame_view = layout_part.ChildFrameView();
     if (frame_view) {
       if (context.tree_builder_context) {
-        context.tree_builder_context->current.paint_offset +=
+        context.tree_builder_context->fragments[0].current.paint_offset +=
             layout_part.ReplacedContentRect().Location() -
             frame_view->FrameRect().Location();
-        context.tree_builder_context->current.paint_offset =
-            RoundedIntPoint(context.tree_builder_context->current.paint_offset);
+        context.tree_builder_context->fragments[0].current.paint_offset =
+            RoundedIntPoint(context.tree_builder_context->fragments[0]
+                                .current.paint_offset);
       }
       Walk(*frame_view, context);
     }
     // TODO(pdr): Investigate RemoteFrameView (crbug.com/579281).
   }
 
   object.GetMutableForPainting().ClearPaintFlags();
 }
 
 }  // namespace blink