1 files changed, 677 insertions, 0 deletions
diff --git a/widget/nsNativeTheme.cpp b/widget/nsNativeTheme.cpp
new file mode 100644
index 0000000000..b758dd5d26
--- /dev/null
+++ b/widget/nsNativeTheme.cpp
@@ -0,0 +1,677 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsNativeTheme.h"
+#include "nsIWidget.h"
+#include "mozilla/dom/Document.h"
+#include "nsIContent.h"
+#include "nsIFrame.h"
+#include "nsIScrollableFrame.h"
+#include "nsNumberControlFrame.h"
+#include "nsPresContext.h"
+#include "nsString.h"
+#include "nsNameSpaceManager.h"
+#include "nsStyleConsts.h"
+#include "nsPIDOMWindow.h"
+#include "nsProgressFrame.h"
+#include "nsMeterFrame.h"
+#include "nsMenuFrame.h"
+#include "nsRangeFrame.h"
+#include "nsCSSRendering.h"
+#include "ImageContainer.h"
+#include "mozilla/ComputedStyle.h"
+#include "mozilla/EventStates.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/HTMLBodyElement.h"
+#include "mozilla/dom/HTMLInputElement.h"
+#include "mozilla/dom/HTMLProgressElement.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/StaticPrefs_layout.h"
+#include "mozilla/dom/DocumentInlines.h"
+#include <algorithm>
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+nsNativeTheme::nsNativeTheme() : mAnimatedContentTimeout(UINT32_MAX) {}
+
+NS_IMPL_ISUPPORTS(nsNativeTheme, nsITimerCallback, nsINamed)
+
+/* static */ EventStates nsNativeTheme::GetContentState(
+    nsIFrame* aFrame, StyleAppearance aAppearance) {
+  if (!aFrame) return EventStates();
+
+  bool isXULCheckboxRadio = (aAppearance == StyleAppearance::Checkbox ||
+                             aAppearance == StyleAppearance::Radio) &&
+                            aFrame->GetContent()->IsXULElement();
+  if (isXULCheckboxRadio) aFrame = aFrame->GetParent();
+
+  if (!aFrame->GetContent()) return EventStates();
+
+  nsIContent* frameContent = aFrame->GetContent();
+  EventStates flags;
+  if (frameContent->IsElement()) {
+    flags = frameContent->AsElement()->State();
+
+    nsNumberControlFrame* numberControlFrame =
+        nsNumberControlFrame::GetNumberControlFrameForSpinButton(aFrame);
+    if (numberControlFrame &&
+        numberControlFrame->GetContent()->AsElement()->State().HasState(
+            NS_EVENT_STATE_DISABLED)) {
+      flags |= NS_EVENT_STATE_DISABLED;
+    }
+  }
+
+  if (isXULCheckboxRadio && aAppearance == StyleAppearance::Radio &&
+      IsFocused(aFrame)) {
+    flags |= NS_EVENT_STATE_FOCUS;
+    nsPIDOMWindowOuter* window = aFrame->GetContent()->OwnerDoc()->GetWindow();
+    if (window && window->ShouldShowFocusRing()) {
+      flags |= NS_EVENT_STATE_FOCUSRING;
+    }
+  }
+
+  return flags;
+}
+
+/* static */
+bool nsNativeTheme::CheckBooleanAttr(nsIFrame* aFrame, nsAtom* aAtom) {
+  if (!aFrame) return false;
+
+  nsIContent* content = aFrame->GetContent();
+  if (!content || !content->IsElement()) return false;
+
+  if (content->IsHTMLElement())
+    return content->AsElement()->HasAttr(kNameSpaceID_None, aAtom);
+
+  // For XML/XUL elements, an attribute must be equal to the literal
+  // string "true" to be counted as true.  An empty string should _not_
+  // be counted as true.
+  return content->AsElement()->AttrValueIs(kNameSpaceID_None, aAtom, u"true"_ns,
+                                           eCaseMatters);
+}
+
+/* static */
+int32_t nsNativeTheme::CheckIntAttr(nsIFrame* aFrame, nsAtom* aAtom,
+                                    int32_t defaultValue) {
+  if (!aFrame) return defaultValue;
+
+  nsIContent* content = aFrame->GetContent();
+  if (!content || !content->IsElement()) return defaultValue;
+
+  nsAutoString attr;
+  content->AsElement()->GetAttr(kNameSpaceID_None, aAtom, attr);
+  nsresult err;
+  int32_t value = attr.ToInteger(&err);
+  if (attr.IsEmpty() || NS_FAILED(err)) return defaultValue;
+
+  return value;
+}
+
+/* static */
+double nsNativeTheme::GetProgressValue(nsIFrame* aFrame) {
+  if (!aFrame || !aFrame->GetContent()->IsHTMLElement(nsGkAtoms::progress)) {
+    return 0;
+  }
+
+  return static_cast<HTMLProgressElement*>(aFrame->GetContent())->Value();
+}
+
+/* static */
+double nsNativeTheme::GetProgressMaxValue(nsIFrame* aFrame) {
+  if (!aFrame || !aFrame->GetContent()->IsHTMLElement(nsGkAtoms::progress)) {
+    return 100;
+  }
+
+  return static_cast<HTMLProgressElement*>(aFrame->GetContent())->Max();
+}
+
+bool nsNativeTheme::GetCheckedOrSelected(nsIFrame* aFrame,
+                                         bool aCheckSelected) {
+  if (!aFrame) return false;
+
+  nsIContent* content = aFrame->GetContent();
+
+  if (content->IsXULElement()) {
+    // For a XUL checkbox or radio button, the state of the parent determines
+    // the checked state
+    aFrame = aFrame->GetParent();
+  } else {
+    // Check for an HTML input element
+    HTMLInputElement* inputElt = HTMLInputElement::FromNode(content);
+    if (inputElt) {
+      return inputElt->Checked();
+    }
+  }
+
+  return CheckBooleanAttr(
+      aFrame, aCheckSelected ? nsGkAtoms::selected : nsGkAtoms::checked);
+}
+
+bool nsNativeTheme::IsButtonTypeMenu(nsIFrame* aFrame) {
+  if (!aFrame) return false;
+
+  nsIContent* content = aFrame->GetContent();
+  return content->IsXULElement(nsGkAtoms::button) &&
+         content->AsElement()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::type,
+                                           u"menu"_ns, eCaseMatters);
+}
+
+bool nsNativeTheme::IsPressedButton(nsIFrame* aFrame) {
+  EventStates eventState =
+      GetContentState(aFrame, StyleAppearance::Toolbarbutton);
+  if (IsDisabled(aFrame, eventState)) return false;
+
+  return IsOpenButton(aFrame) ||
+         eventState.HasAllStates(NS_EVENT_STATE_ACTIVE | NS_EVENT_STATE_HOVER);
+}
+
+bool nsNativeTheme::GetIndeterminate(nsIFrame* aFrame) {
+  if (!aFrame) return false;
+
+  nsIContent* content = aFrame->GetContent();
+
+  if (content->IsXULElement()) {
+    // For a XUL checkbox or radio button, the state of the parent determines
+    // the state
+    return CheckBooleanAttr(aFrame->GetParent(), nsGkAtoms::indeterminate);
+  }
+
+  // Check for an HTML input element
+  HTMLInputElement* inputElt = HTMLInputElement::FromNode(content);
+  if (inputElt) {
+    return inputElt->Indeterminate();
+  }
+
+  return false;
+}
+
+bool nsNativeTheme::IsWidgetStyled(nsPresContext* aPresContext,
+                                   nsIFrame* aFrame,
+                                   StyleAppearance aAppearance) {
+  // Check for specific widgets to see if HTML has overridden the style.
+  if (!aFrame) return false;
+
+  // Resizers have some special handling, dependent on whether in a scrollable
+  // container or not. If so, use the scrollable container's to determine
+  // whether the style is overriden instead of the resizer. This allows a
+  // non-native transparent resizer to be used instead. Otherwise, we just
+  // fall through and return false.
+  if (aAppearance == StyleAppearance::Resizer) {
+    nsIFrame* parentFrame = aFrame->GetParent();
+    if (parentFrame && parentFrame->IsScrollFrame()) {
+      // if the parent is a scrollframe, the resizer should be native themed
+      // only if the scrollable area doesn't override the widget style.
+      parentFrame = parentFrame->GetParent();
+      if (parentFrame) {
+        return IsWidgetStyled(
+            aPresContext, parentFrame,
+            parentFrame->StyleDisplay()->EffectiveAppearance());
+      }
+    }
+  }
+
+  /**
+   * Progress bar appearance should be the same for the bar and the container
+   * frame. nsProgressFrame owns the logic and will tell us what we should do.
+   */
+  if (aAppearance == StyleAppearance::Progresschunk ||
+      aAppearance == StyleAppearance::ProgressBar) {
+    nsProgressFrame* progressFrame = do_QueryFrame(
+        aAppearance == StyleAppearance::Progresschunk ? aFrame->GetParent()
+                                                      : aFrame);
+    if (progressFrame) {
+      return !progressFrame->ShouldUseNativeStyle();
+    }
+  }
+
+  /**
+   * Meter bar appearance should be the same for the bar and the container
+   * frame. nsMeterFrame owns the logic and will tell us what we should do.
+   */
+  if (aAppearance == StyleAppearance::Meterchunk ||
+      aAppearance == StyleAppearance::Meter) {
+    nsMeterFrame* meterFrame = do_QueryFrame(
+        aAppearance == StyleAppearance::Meterchunk ? aFrame->GetParent()
+                                                   : aFrame);
+    if (meterFrame) {
+      return !meterFrame->ShouldUseNativeStyle();
+    }
+  }
+
+  /**
+   * An nsRangeFrame and its children are treated atomically when it
+   * comes to native theming (either all parts, or no parts, are themed).
+   * nsRangeFrame owns the logic and will tell us what we should do.
+   */
+  if (aAppearance == StyleAppearance::Range ||
+      aAppearance == StyleAppearance::RangeThumb) {
+    nsRangeFrame* rangeFrame = do_QueryFrame(
+        aAppearance == StyleAppearance::RangeThumb ? aFrame->GetParent()
+                                                   : aFrame);
+    if (rangeFrame) {
+      return !rangeFrame->ShouldUseNativeStyle();
+    }
+  }
+
+  if (aAppearance == StyleAppearance::SpinnerUpbutton ||
+      aAppearance == StyleAppearance::SpinnerDownbutton) {
+    nsNumberControlFrame* numberControlFrame =
+        nsNumberControlFrame::GetNumberControlFrameForSpinButton(aFrame);
+    if (numberControlFrame) {
+      return !numberControlFrame->ShouldUseNativeStyleForSpinner();
+    }
+  }
+
+  return (aAppearance == StyleAppearance::NumberInput ||
+          aAppearance == StyleAppearance::Button ||
+          aAppearance == StyleAppearance::Textfield ||
+          aAppearance == StyleAppearance::Textarea ||
+          aAppearance == StyleAppearance::Listbox ||
+          aAppearance == StyleAppearance::Menulist ||
+          aAppearance == StyleAppearance::MenulistButton) &&
+         aFrame->GetContent()->IsHTMLElement() &&
+         aPresContext->HasAuthorSpecifiedRules(
+             aFrame, NS_AUTHOR_SPECIFIED_BORDER_OR_BACKGROUND);
+}
+
+bool nsNativeTheme::IsDisabled(nsIFrame* aFrame, EventStates aEventStates) {
+  if (!aFrame) {
+    return false;
+  }
+
+  nsIContent* content = aFrame->GetContent();
+  if (!content || !content->IsElement()) {
+    return false;
+  }
+
+  if (content->IsHTMLElement()) {
+    return aEventStates.HasState(NS_EVENT_STATE_DISABLED);
+  }
+
+  // For XML/XUL elements, an attribute must be equal to the literal
+  // string "true" to be counted as true.  An empty string should _not_
+  // be counted as true.
+  return content->AsElement()->AttrValueIs(
+      kNameSpaceID_None, nsGkAtoms::disabled, u"true"_ns, eCaseMatters);
+}
+
+/* static */
+bool nsNativeTheme::IsFrameRTL(nsIFrame* aFrame) {
+  if (!aFrame) {
+    return false;
+  }
+  return aFrame->GetWritingMode().IsPhysicalRTL();
+}
+
+/* static */
+bool nsNativeTheme::IsHTMLContent(nsIFrame* aFrame) {
+  if (!aFrame) {
+    return false;
+  }
+  nsIContent* content = aFrame->GetContent();
+  return content && content->IsHTMLElement();
+}
+
+// scrollbar button:
+int32_t nsNativeTheme::GetScrollbarButtonType(nsIFrame* aFrame) {
+  if (!aFrame) return 0;
+
+  static Element::AttrValuesArray strings[] = {
+      nsGkAtoms::scrollbarDownBottom, nsGkAtoms::scrollbarDownTop,
+      nsGkAtoms::scrollbarUpBottom, nsGkAtoms::scrollbarUpTop, nullptr};
+
+  nsIContent* content = aFrame->GetContent();
+  if (!content || !content->IsElement()) {
+    return 0;
+  }
+
+  switch (content->AsElement()->FindAttrValueIn(
+      kNameSpaceID_None, nsGkAtoms::sbattr, strings, eCaseMatters)) {
+    case 0:
+      return eScrollbarButton_Down | eScrollbarButton_Bottom;
+    case 1:
+      return eScrollbarButton_Down;
+    case 2:
+      return eScrollbarButton_Bottom;
+    case 3:
+      return eScrollbarButton_UpTop;
+  }
+
+  return 0;
+}
+
+// treeheadercell:
+nsNativeTheme::TreeSortDirection nsNativeTheme::GetTreeSortDirection(
+    nsIFrame* aFrame) {
+  if (!aFrame || !aFrame->GetContent()) return eTreeSortDirection_Natural;
+
+  static Element::AttrValuesArray strings[] = {nsGkAtoms::descending,
+                                               nsGkAtoms::ascending, nullptr};
+
+  nsIContent* content = aFrame->GetContent();
+  if (content->IsElement()) {
+    switch (content->AsElement()->FindAttrValueIn(
+        kNameSpaceID_None, nsGkAtoms::sortDirection, strings, eCaseMatters)) {
+      case 0:
+        return eTreeSortDirection_Descending;
+      case 1:
+        return eTreeSortDirection_Ascending;
+    }
+  }
+
+  return eTreeSortDirection_Natural;
+}
+
+bool nsNativeTheme::IsLastTreeHeaderCell(nsIFrame* aFrame) {
+  if (!aFrame) return false;
+
+  // A tree column picker is always the last header cell.
+  if (aFrame->GetContent()->IsXULElement(nsGkAtoms::treecolpicker)) return true;
+
+  // Find the parent tree.
+  nsIContent* parent = aFrame->GetContent()->GetParent();
+  while (parent && !parent->IsXULElement(nsGkAtoms::tree)) {
+    parent = parent->GetParent();
+  }
+
+  // If the column picker is visible, this can't be the last column.
+  if (parent && !parent->AsElement()->AttrValueIs(kNameSpaceID_None,
+                                                  nsGkAtoms::hidecolumnpicker,
+                                                  u"true"_ns, eCaseMatters))
+    return false;
+
+  while ((aFrame = aFrame->GetNextSibling())) {
+    if (aFrame->GetRect().Width() > 0) return false;
+  }
+  return true;
+}
+
+// tab:
+bool nsNativeTheme::IsBottomTab(nsIFrame* aFrame) {
+  if (!aFrame) return false;
+
+  nsAutoString classStr;
+  if (aFrame->GetContent()->IsElement()) {
+    aFrame->GetContent()->AsElement()->GetAttr(kNameSpaceID_None,
+                                               nsGkAtoms::_class, classStr);
+  }
+  // FIXME: This looks bogus, shouldn't this be looking at GetClasses()?
+  return !classStr.IsEmpty() && classStr.Find("tab-bottom") != kNotFound;
+}
+
+bool nsNativeTheme::IsFirstTab(nsIFrame* aFrame) {
+  if (!aFrame) return false;
+
+  for (nsIFrame* first : aFrame->GetParent()->PrincipalChildList()) {
+    if (first->GetRect().Width() > 0 &&
+        first->GetContent()->IsXULElement(nsGkAtoms::tab))
+      return (first == aFrame);
+  }
+  return false;
+}
+
+bool nsNativeTheme::IsHorizontal(nsIFrame* aFrame) {
+  if (!aFrame) return false;
+
+  if (!aFrame->GetContent()->IsElement()) return true;
+
+  return !aFrame->GetContent()->AsElement()->AttrValueIs(
+      kNameSpaceID_None, nsGkAtoms::orient, nsGkAtoms::vertical, eCaseMatters);
+}
+
+bool nsNativeTheme::IsNextToSelectedTab(nsIFrame* aFrame, int32_t aOffset) {
+  if (!aFrame) return false;
+
+  if (aOffset == 0) return IsSelectedTab(aFrame);
+
+  int32_t thisTabIndex = -1, selectedTabIndex = -1;
+
+  nsIFrame* currentTab = aFrame->GetParent()->PrincipalChildList().FirstChild();
+  for (int32_t i = 0; currentTab; currentTab = currentTab->GetNextSibling()) {
+    if (currentTab->GetRect().Width() == 0) continue;
+    if (aFrame == currentTab) thisTabIndex = i;
+    if (IsSelectedTab(currentTab)) selectedTabIndex = i;
+    ++i;
+  }
+
+  if (thisTabIndex == -1 || selectedTabIndex == -1) return false;
+
+  return (thisTabIndex - selectedTabIndex == aOffset);
+}
+
+bool nsNativeTheme::IsIndeterminateProgress(nsIFrame* aFrame,
+                                            EventStates aEventStates) {
+  if (!aFrame || !aFrame->GetContent() ||
+      !aFrame->GetContent()->IsHTMLElement(nsGkAtoms::progress)) {
+    return false;
+  }
+
+  return aEventStates.HasState(NS_EVENT_STATE_INDETERMINATE);
+}
+
+bool nsNativeTheme::IsVerticalProgress(nsIFrame* aFrame) {
+  if (!aFrame) {
+    return false;
+  }
+  return IsVerticalMeter(aFrame);
+}
+
+bool nsNativeTheme::IsVerticalMeter(nsIFrame* aFrame) {
+  MOZ_ASSERT(aFrame, "You have to pass a non-null aFrame");
+  switch (aFrame->StyleDisplay()->mOrient) {
+    case StyleOrient::Horizontal:
+      return false;
+    case StyleOrient::Vertical:
+      return true;
+    case StyleOrient::Inline:
+      return aFrame->GetWritingMode().IsVertical();
+    case StyleOrient::Block:
+      return !aFrame->GetWritingMode().IsVertical();
+  }
+  MOZ_ASSERT_UNREACHABLE("unexpected -moz-orient value");
+  return false;
+}
+
+// menupopup:
+bool nsNativeTheme::IsSubmenu(nsIFrame* aFrame, bool* aLeftOfParent) {
+  if (!aFrame) return false;
+
+  nsIContent* parentContent = aFrame->GetContent()->GetParent();
+  if (!parentContent || !parentContent->IsXULElement(nsGkAtoms::menu))
+    return false;
+
+  nsIFrame* parent = aFrame;
+  while ((parent = parent->GetParent())) {
+    if (parent->GetContent() == parentContent) {
+      if (aLeftOfParent) {
+        LayoutDeviceIntRect selfBounds, parentBounds;
+        selfBounds = aFrame->GetNearestWidget()->GetScreenBounds();
+        parentBounds = parent->GetNearestWidget()->GetScreenBounds();
+        *aLeftOfParent = selfBounds.X() < parentBounds.X();
+      }
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool nsNativeTheme::IsRegularMenuItem(nsIFrame* aFrame) {
+  nsMenuFrame* menuFrame = do_QueryFrame(aFrame);
+  return !(menuFrame &&
+           (menuFrame->IsOnMenuBar() || menuFrame->IsParentMenuList()));
+}
+
+bool nsNativeTheme::QueueAnimatedContentForRefresh(nsIContent* aContent,
+                                                   uint32_t aMinimumFrameRate) {
+  NS_ASSERTION(aContent, "Null pointer!");
+  NS_ASSERTION(aMinimumFrameRate, "aMinimumFrameRate must be non-zero!");
+  NS_ASSERTION(aMinimumFrameRate <= 1000,
+               "aMinimumFrameRate must be less than 1000!");
+
+  uint32_t timeout = 1000 / aMinimumFrameRate;
+  timeout = std::min(mAnimatedContentTimeout, timeout);
+
+  if (!mAnimatedContentTimer) {
+    mAnimatedContentTimer = NS_NewTimer();
+    NS_ENSURE_TRUE(mAnimatedContentTimer, false);
+  }
+
+  if (mAnimatedContentList.IsEmpty() || timeout != mAnimatedContentTimeout) {
+    nsresult rv;
+    if (!mAnimatedContentList.IsEmpty()) {
+      rv = mAnimatedContentTimer->Cancel();
+      NS_ENSURE_SUCCESS(rv, false);
+    }
+
+    if (XRE_IsContentProcess() && NS_IsMainThread()) {
+      mAnimatedContentTimer->SetTarget(
+          aContent->OwnerDoc()->EventTargetFor(TaskCategory::Other));
+    }
+    rv = mAnimatedContentTimer->InitWithCallback(this, timeout,
+                                                 nsITimer::TYPE_ONE_SHOT);
+    NS_ENSURE_SUCCESS(rv, false);
+
+    mAnimatedContentTimeout = timeout;
+  }
+
+  // XXX(Bug 1631371) Check if this should use a fallible operation as it
+  // pretended earlier.
+  mAnimatedContentList.AppendElement(aContent);
+
+  return true;
+}
+
+NS_IMETHODIMP
+nsNativeTheme::Notify(nsITimer* aTimer) {
+  NS_ASSERTION(aTimer == mAnimatedContentTimer, "Wrong timer!");
+
+  // XXX Assumes that calling nsIFrame::Invalidate won't reenter
+  //     QueueAnimatedContentForRefresh.
+
+  uint32_t count = mAnimatedContentList.Length();
+  for (uint32_t index = 0; index < count; index++) {
+    nsIFrame* frame = mAnimatedContentList[index]->GetPrimaryFrame();
+    if (frame) {
+      frame->InvalidateFrame();
+    }
+  }
+
+  mAnimatedContentList.Clear();
+  mAnimatedContentTimeout = UINT32_MAX;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsNativeTheme::GetName(nsACString& aName) {
+  aName.AssignLiteral("nsNativeTheme");
+  return NS_OK;
+}
+
+nsIFrame* nsNativeTheme::GetAdjacentSiblingFrameWithSameAppearance(
+    nsIFrame* aFrame, bool aNextSibling) {
+  if (!aFrame) return nullptr;
+
+  // Find the next visible sibling.
+  nsIFrame* sibling = aFrame;
+  do {
+    sibling =
+        aNextSibling ? sibling->GetNextSibling() : sibling->GetPrevSibling();
+  } while (sibling && sibling->GetRect().Width() == 0);
+
+  // Check same appearance and adjacency.
+  if (!sibling ||
+      sibling->StyleDisplay()->EffectiveAppearance() !=
+          aFrame->StyleDisplay()->EffectiveAppearance() ||
+      (sibling->GetRect().XMost() != aFrame->GetRect().X() &&
+       aFrame->GetRect().XMost() != sibling->GetRect().X()))
+    return nullptr;
+  return sibling;
+}
+
+bool nsNativeTheme::IsRangeHorizontal(nsIFrame* aFrame) {
+  nsIFrame* rangeFrame = aFrame;
+  if (!rangeFrame->IsRangeFrame()) {
+    // If the thumb's frame is passed in, get its range parent:
+    rangeFrame = aFrame->GetParent();
+  }
+  if (rangeFrame->IsRangeFrame()) {
+    return static_cast<nsRangeFrame*>(rangeFrame)->IsHorizontal();
+  }
+  // Not actually a range frame - just use the ratio of the frame's size to
+  // decide:
+  return aFrame->GetSize().width >= aFrame->GetSize().height;
+}
+
+static nsIFrame* GetBodyFrame(nsIFrame* aCanvasFrame) {
+  nsIContent* content = aCanvasFrame->GetContent();
+  if (!content) {
+    return nullptr;
+  }
+  nsIContent* body = content->OwnerDoc()->GetBodyElement();
+  if (!body) {
+    return nullptr;
+  }
+  return body->GetPrimaryFrame();
+}
+
+/* static */
+bool nsNativeTheme::IsDarkBackground(nsIFrame* aFrame) {
+  nsIScrollableFrame* scrollFrame = nullptr;
+  while (!scrollFrame && aFrame) {
+    scrollFrame = aFrame->GetScrollTargetFrame();
+    aFrame = aFrame->GetParent();
+  }
+  if (!scrollFrame) return false;
+
+  nsIFrame* frame = scrollFrame->GetScrolledFrame();
+  if (nsCSSRendering::IsCanvasFrame(frame)) {
+    // For canvas frames, prefer to look at the body first, because the body
+    // background color is most likely what will be visible as the background
+    // color of the page, even if the html element has a different background
+    // color which prevents that of the body frame to propagate to the viewport.
+    nsIFrame* bodyFrame = GetBodyFrame(frame);
+    if (bodyFrame) {
+      frame = bodyFrame;
+    }
+  }
+  ComputedStyle* bgSC = nullptr;
+  if (!nsCSSRendering::FindBackground(frame, &bgSC) ||
+      bgSC->StyleBackground()->IsTransparent(bgSC)) {
+    nsIFrame* backgroundFrame =
+        nsCSSRendering::FindNonTransparentBackgroundFrame(frame, true);
+    nsCSSRendering::FindBackground(backgroundFrame, &bgSC);
+  }
+  if (bgSC) {
+    nscolor bgColor = bgSC->StyleBackground()->BackgroundColor(bgSC);
+    // Consider the background color dark if the sum of the r, g and b values is
+    // less than 384 in a semi-transparent document.  This heuristic matches
+    // what WebKit does, and we can improve it later if needed.
+    return NS_GET_A(bgColor) > 127 &&
+           NS_GET_R(bgColor) + NS_GET_G(bgColor) + NS_GET_B(bgColor) < 384;
+  }
+  return false;
+}
+
+/*static*/
+bool nsNativeTheme::IsWidgetScrollbarPart(StyleAppearance aAppearance) {
+  switch (aAppearance) {
+    case StyleAppearance::ScrollbarVertical:
+    case StyleAppearance::ScrollbarHorizontal:
+    case StyleAppearance::ScrollbarbuttonUp:
+    case StyleAppearance::ScrollbarbuttonDown:
+    case StyleAppearance::ScrollbarbuttonLeft:
+    case StyleAppearance::ScrollbarbuttonRight:
+    case StyleAppearance::ScrollbarthumbVertical:
+    case StyleAppearance::ScrollbarthumbHorizontal:
+    case StyleAppearance::ScrollbartrackHorizontal:
+    case StyleAppearance::ScrollbartrackVertical:
+    case StyleAppearance::Scrollcorner:
+      return true;
+    default:
+      return false;
+  }
+}