[SPInvalidation, SPv2] Compute paint offset for paginated content

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

 // Copyright 2014 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/PaintLayerPainter.h"
 
 #include "core/frame/LocalFrame.h"
 #include "core/layout/LayoutView.h"
 #include "core/paint/ClipPathClipper.h"
 #include "core/paint/FilterPainter.h"
@@ skipping 424 matching lines @@
       paint_layer_.ConvertToLayerCoords(local_painting_info.root_layer,
                                         offset_to_clipper);
       local_painting_info.paint_dirty_rect.MoveBy(offset_to_clipper);
     }
 
     PaintLayer::GeometryMapperOption geometry_mapper_option =
         PaintLayer::kDoNotUseGeometryMapper;
     if (RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled())
       geometry_mapper_option = PaintLayer::kUseGeometryMapper;
 
-    // TODO(trchen): We haven't decided how to handle visual fragmentation with
-    // SPv2.  Related thread
-    // https://groups.google.com/a/chromium.org/forum/#!topic/graphics-dev/81XuWFf-mxM
-    if (fragment_policy == kForceSingleFragment ||
-        RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
+    if (fragment_policy == kForceSingleFragment) {
       paint_layer_for_fragments->AppendSingleFragmentIgnoringPagination(
           layer_fragments, local_painting_info.root_layer,
           local_painting_info.paint_dirty_rect, cache_slot,
           geometry_mapper_option, kIgnorePlatformOverlayScrollbarSize,
           respect_overflow_clip, &offset_from_root,
           local_painting_info.sub_pixel_accumulation);
     } else if (IsFixedPositionObjectInPagedMedia()) {
       PaintLayerFragments single_fragment;
       paint_layer_for_fragments->AppendSingleFragmentIgnoringPagination(
           single_fragment, local_painting_info.root_layer,
@@ skipping 523 matching lines @@
   // We know that the mask just needs the area bounded by the clip rects to be
   // filled with black.
   if (clip_recorder && phase == kPaintPhaseClippingMask) {
     FillMaskingFragment(context, clip_rect);
     return;
   }
 
   LayoutRect new_cull_rect(clip_rect.Rect());
   Optional<ScrollRecorder> scroll_recorder;
   LayoutPoint paint_offset = -paint_layer_.LayoutBoxLocation();
-  if (RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
+  if (RuntimeEnabledFeatures::slimmingPaintV2Enabled() &&
+      !paint_layer_.EnclosingPaginationLayer()) {
     paint_offset += paint_layer_.GetLayoutObject().PaintOffset();
     new_cull_rect.Move(painting_info.scroll_offset_accumulation);
   } else {
     paint_offset += ToSize(fragment.layer_bounds.Location());
     if (!painting_info.scroll_offset_accumulation.IsZero()) {
       // As a descendant of the root layer, m_paintLayer's painting is not
       // controlled by the ScrollRecorders created by BlockPainter of the
       // ancestor layers up to the root layer, so we need to issue
       // ScrollRecorder for this layer seperately, with the scroll offset
       // accumulated from the root layer to the parent of this layer, to get the
@@ skipping 214 matching lines @@
           context, layout_object, kPaintPhaseClippingMask))
     return;
 
   IntRect snapped_clip_rect = PixelSnappedIntRect(clip_rect.Rect());
   LayoutObjectDrawingRecorder drawing_recorder(
       context, layout_object, kPaintPhaseClippingMask, snapped_clip_rect);
   context.FillRect(snapped_clip_rect, Color::kBlack);
 }
 
 }  // namespace blink