[Controls Refresh] Dark mode scrollbars are not dynamically updated bugfix

This CL addresses a bug in which, when the OS color scheme is changed, the scrollbars on the page maintain their old color scheme.

Bug: 1137169
Change-Id: I22416b906aa06e0476dc298fd2d3a0e9653305d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2522563Reviewed-by: Yu Han <yuzhehan@chromium.org>
Reviewed-by: Mason Freed <masonfreed@chromium.org>
Commit-Queue: Sam Sebree <sasebree@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#826430}

third_party/blink/renderer/core/dom/document.cc

@@ -8477,11 +8477,24 @@ void Document::SetShowBeforeUnloadDialog(bool show_dialog) {
 }
 
 void Document::ColorSchemeChanged() {
+  InvalidateScrollbars();
   UpdateForcedColors();
   GetStyleEngine().ColorSchemeChanged();
   MediaQueryAffectingValueChanged(MediaValueChange::kOther);
 }
 
+void Document::InvalidateScrollbars() {
+  if (PaintLayerScrollableArea* scrollable_area =
+          GetLayoutView()->GetScrollableArea()) {
+    if (auto* horizontal_scrollbar = scrollable_area->HorizontalScrollbar()) {
+      horizontal_scrollbar->SetNeedsPaintInvalidation(kAllParts);
+    }
+    if (auto* vertical_scrollbar = scrollable_area->VerticalScrollbar()) {
+      vertical_scrollbar->SetNeedsPaintInvalidation(kAllParts);
+    }
+  }
+}
+
 void Document::VisionDeficiencyChanged() {
   GetStyleEngine().VisionDeficiencyChanged();
 }

third_party/blink/renderer/core/dom/document.h

@@ -1724,6 +1724,8 @@ class CORE_EXPORT Document : public ContainerNode,
 
   void PropagateStyleToViewport();
 
+  void InvalidateScrollbars();
+
   void UpdateUseShadowTreesIfNeeded();
   void EvaluateMediaQueryListIfNeeded();