Cleanup PaintLayerScrollableArea about paint invalidation

Some code was left when we separated paint invalidation and raster
invalidation. Some perhaps were caused by cleaning up for raster
invalidation and root-layer-scrolling at the same time.

Change-Id: I8d26291941f17f555c1e09ba0483d41c4c4bfe47
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1826994Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#702146}

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

@@ -89,7 +89,6 @@
 #include "third_party/blink/renderer/core/page/scrolling/top_document_root_scroller_controller.h"
 #include "third_party/blink/renderer/core/paint/compositing/composited_layer_mapping.h"
 #include "third_party/blink/renderer/core/paint/compositing/paint_layer_compositor.h"
-#include "third_party/blink/renderer/core/paint/find_paint_offset_and_visual_rect_needing_update.h"
 #include "third_party/blink/renderer/core/paint/paint_invalidator.h"
 #include "third_party/blink/renderer/core/paint/paint_layer_fragment.h"
 #include "third_party/blink/renderer/core/scroll/scroll_alignment.h"
@@ -2626,41 +2625,20 @@ void PaintLayerScrollableArea::WillRemoveScrollbar(
   ScrollableArea::WillRemoveScrollbar(scrollbar, orientation);
 }
 
-static IntRect ScrollControlVisualRect(const IntRect& scroll_control_rect,
-                                       const LayoutBox& box,
-                                       const PaintInvalidatorContext& context,
-                                       const IntRect& previous_visual_rect) {
-  IntRect visual_rect(scroll_control_rect);
-#if DCHECK_IS_ON()
-  FindVisualRectNeedingUpdateScope finder(box, context, previous_visual_rect,
-                                          visual_rect);
-#endif
-  if (!context.NeedsVisualRectUpdate(box))
-    return previous_visual_rect;
-
-  // No need to apply any paint offset. Scroll controls paint in a different
-  // transform space than their contained box (the scrollbarPaintOffset
-  // transform node).
-  return visual_rect;
-}
-
 // Returns true if the scroll control is invalidated.
-static bool InvalidatePaintOfScrollControlIfNeeded(
+static bool ScrollControlNeedsPaintInvalidation(
     const IntRect& new_visual_rect,
     const IntRect& previous_visual_rect,
-    bool needs_paint_invalidation,
-    LayoutBox& box,
-    const LayoutBoxModelObject& paint_invalidation_container) {
-  bool should_invalidate_new_rect = needs_paint_invalidation;
-  if (new_visual_rect != previous_visual_rect) {
-    should_invalidate_new_rect = true;
-  } else if (previous_visual_rect.IsEmpty()) {
+    bool needs_paint_invalidation) {
+  if (new_visual_rect != previous_visual_rect)
+    return true;
+  if (previous_visual_rect.IsEmpty()) {
     DCHECK(new_visual_rect.IsEmpty());
     // Do not issue an empty invalidation.
-    should_invalidate_new_rect = false;
+    return false;
   }
 
-  return should_invalidate_new_rect;
+  return needs_paint_invalidation;
 }
 
 static IntRect InvalidatePaintOfScrollbarIfNeeded(
@@ -2675,22 +2653,14 @@ static IntRect InvalidatePaintOfScrollbarIfNeeded(
   bool is_overlay = scrollbar && scrollbar->IsOverlayScrollbar();
 
   IntRect new_visual_rect;
-  // Calculate visual rect of the scrollbar, except overlay composited
-  // scrollbars because we invalidate the graphics layer only.
-  if (scrollbar && !(graphics_layer && is_overlay)) {
-    new_visual_rect = ScrollControlVisualRect(scrollbar->FrameRect(), box,
-                                              context, previous_visual_rect);
-  }
+  if (scrollbar)
+    new_visual_rect = scrollbar->FrameRect();
 
   if (needs_paint_invalidation && graphics_layer) {
     // If the scrollbar needs paint invalidation but didn't change location/size
     // or the scrollbar is an overlay scrollbar (visual rect is empty),
     // invalidating the graphics layer is enough (which has been done in
     // ScrollableArea::setScrollbarNeedsPaintInvalidation()).
-    // Otherwise invalidatePaintOfScrollControlIfNeeded() below will invalidate
-    // the old and new location of the scrollbar on the box's paint invalidation
-    // container to ensure newly expanded/shrunk areas of the box to be
-    // invalidated.
     needs_paint_invalidation = false;
     DCHECK(!graphics_layer->PaintsContentOrHitTest() ||
            graphics_layer->GetPaintController().GetPaintArtifact().IsEmpty());
@@ -2698,12 +2668,10 @@ static IntRect InvalidatePaintOfScrollbarIfNeeded(
 
   // Invalidate the box's display item client if the box's padding box size is
   // affected by change of the non-overlay scrollbar width. We detect change of
-  // visual rect size instead of change of scrollbar width change, which may
-  // have some false-positives (e.g. the scrollbar changed length but not width)
-  // but won't invalidate more than expected because in the false-positive case
-  // the box must have changed size and have been invalidated.
-  const LayoutBoxModelObject& paint_invalidation_container =
-      *context.paint_invalidation_container;
+  // visual rect size instead of change of scrollbar width, which may have some
+  // false-positives (e.g. the scrollbar changed length but not width) but won't
+  // invalidate more than expected because in the false-positive case the box
+  // must have changed size and have been invalidated.
   IntSize new_scrollbar_used_space_in_box;
   if (!is_overlay)
     new_scrollbar_used_space_in_box = new_visual_rect.Size();
@@ -2723,13 +2691,11 @@ static IntRect InvalidatePaintOfScrollbarIfNeeded(
     box_geometry_has_been_invalidated = true;
   }
 
-  bool invalidated = InvalidatePaintOfScrollControlIfNeeded(
-      new_visual_rect, previous_visual_rect, needs_paint_invalidation, box,
-      paint_invalidation_container);
-
   previously_was_overlay = is_overlay;
 
-  if (!invalidated || !scrollbar || graphics_layer)
+  if (!scrollbar || graphics_layer ||
+      !ScrollControlNeedsPaintInvalidation(
+          new_visual_rect, previous_visual_rect, needs_paint_invalidation))
     return new_visual_rect;
 
   context.painting_layer->SetNeedsRepaint();
@@ -2760,16 +2726,11 @@ void PaintLayerScrollableArea::InvalidatePaintOfScrollControlsIfNeeded(
       VerticalScrollbarNeedsPaintInvalidation(), box,
       box_geometry_has_been_invalidated, context));
 
-  IntRect scroll_corner_and_resizer_visual_rect =
-      ScrollControlVisualRect(ScrollCornerAndResizerRect(), box, context,
-                              scroll_corner_and_resizer_visual_rect_);
-  const LayoutBoxModelObject& paint_invalidation_container =
-      *context.paint_invalidation_container;
-  if (InvalidatePaintOfScrollControlIfNeeded(
+  IntRect scroll_corner_and_resizer_visual_rect = ScrollCornerAndResizerRect();
+  if (ScrollControlNeedsPaintInvalidation(
           scroll_corner_and_resizer_visual_rect,
           scroll_corner_and_resizer_visual_rect_,
-          ScrollCornerNeedsPaintInvalidation(), box,
-          paint_invalidation_container)) {
+          ScrollCornerNeedsPaintInvalidation())) {
     SetScrollCornerAndResizerVisualRect(scroll_corner_and_resizer_visual_rect);
     if (LayoutScrollbarPart* scroll_corner = ScrollCorner()) {
       ObjectPaintInvalidator(*scroll_corner)