Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3226 insertions, 0 deletions

diff --git a/layout/base/nsLayoutUtils.h b/layout/base/nsLayoutUtils.h
new file mode 100644
index 0000000000..ce6d06c109
--- /dev/null
+++ b/layout/base/nsLayoutUtils.h
@@ -0,0 +1,3226 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef nsLayoutUtils_h__
+#define nsLayoutUtils_h__
+
+#include "LayoutConstants.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/LookAndFeel.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/RelativeTo.h"
+#include "mozilla/StaticPrefs_nglayout.h"
+#include "mozilla/SurfaceFromElementResult.h"
+#include "mozilla/SVGImageContext.h"
+#include "mozilla/ToString.h"
+#include "mozilla/TypedEnumBits.h"
+#include "mozilla/Span.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/WritingModes.h"
+#include "mozilla/layers/ScrollableLayerGuid.h"
+#include "mozilla/gfx/2D.h"
+
+#include "gfxPoint.h"
+#include "nsBoundingMetrics.h"
+#include "nsCSSPropertyIDSet.h"
+#include "nsFrameList.h"
+#include "nsThreadUtils.h"
+#include "Units.h"
+#include "mozilla/layers/LayersTypes.h"
+#include <limits>
+#include <algorithm>
+// If you're thinking of adding a new include here, please try hard to not.
+// This header file gets included just about everywhere and adding headers here
+// can dramatically increase avoidable build activity. Try instead:
+// - using a forward declaration
+// - putting the include in the .cpp file, if it is only needed by the body
+// - putting your new functions in some other less-widely-used header
+
+class gfxContext;
+class gfxFontEntry;
+class imgIContainer;
+class nsFrameList;
+class nsPresContext;
+class nsIContent;
+class nsIPrincipal;
+class nsIWidget;
+class nsAtom;
+class nsIScrollableFrame;
+class nsRegion;
+enum nsChangeHint : uint32_t;
+class nsFontMetrics;
+class nsFontFaceList;
+class nsIImageLoadingContent;
+class nsBlockFrame;
+class nsContainerFrame;
+class nsView;
+class nsIFrame;
+class nsPIDOMWindowOuter;
+class imgIRequest;
+struct nsStyleFont;
+
+namespace mozilla {
+class nsDisplayItem;
+class nsDisplayList;
+class nsDisplayListBuilder;
+enum class nsDisplayListBuilderMode : uint8_t;
+class RetainedDisplayListBuilder;
+struct AspectRatio;
+class ComputedStyle;
+class DisplayPortUtils;
+class PresShell;
+enum class PseudoStyleType : uint8_t;
+class EventListenerManager;
+enum class LayoutFrameType : uint8_t;
+struct IntrinsicSize;
+class ReflowOutput;
+class WritingMode;
+class DisplayItemClip;
+class EffectSet;
+struct ActiveScrolledRoot;
+enum class ScrollOrigin : uint8_t;
+enum class StyleImageOrientation : uint8_t;
+enum class StyleSystemFont : uint8_t;
+enum class StyleScrollbarWidth : uint8_t;
+struct OverflowAreas;
+namespace dom {
+class CanvasRenderingContext2D;
+class DOMRectList;
+class Document;
+class Element;
+class Event;
+class HTMLImageElement;
+class HTMLCanvasElement;
+class HTMLVideoElement;
+class ImageBitmap;
+class InspectorFontFace;
+class OffscreenCanvas;
+class Selection;
+}  // namespace dom
+namespace gfx {
+struct RectCornerRadii;
+enum class ShapedTextFlags : uint16_t;
+}  // namespace gfx
+namespace image {
+class ImageIntRegion;
+struct Resolution;
+}  // namespace image
+namespace layers {
+struct FrameMetrics;
+struct ScrollMetadata;
+class Image;
+class StackingContextHelper;
+class Layer;
+class WebRenderLayerManager;
+
+}  // namespace layers
+}  // namespace mozilla
+
+// Flags to customize the behavior of nsLayoutUtils::DrawString.
+enum class DrawStringFlags {
+  Default = 0x0,
+  ForceHorizontal = 0x1  // Forces the text to be drawn horizontally.
+};
+MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(DrawStringFlags)
+
+namespace mozilla {
+
+class RectCallback {
+ public:
+  virtual void AddRect(const nsRect& aRect) = 0;
+};
+
+}  // namespace mozilla
+
+/**
+ * nsLayoutUtils is a namespace class used for various helper
+ * functions that are useful in multiple places in layout.  The goal
+ * is not to define multiple copies of the same static helper.
+ */
+class nsLayoutUtils {
+  typedef mozilla::AspectRatio AspectRatio;
+  typedef mozilla::ComputedStyle ComputedStyle;
+  typedef mozilla::LengthPercentage LengthPercentage;
+  typedef mozilla::LengthPercentageOrAuto LengthPercentageOrAuto;
+  typedef mozilla::dom::DOMRectList DOMRectList;
+  typedef mozilla::layers::StackingContextHelper StackingContextHelper;
+  typedef mozilla::IntrinsicSize IntrinsicSize;
+  typedef mozilla::RelativeTo RelativeTo;
+  typedef mozilla::ScrollOrigin ScrollOrigin;
+  typedef mozilla::ViewportType ViewportType;
+  typedef mozilla::gfx::SourceSurface SourceSurface;
+  typedef mozilla::gfx::sRGBColor sRGBColor;
+  typedef mozilla::gfx::DrawTarget DrawTarget;
+  typedef mozilla::gfx::ExtendMode ExtendMode;
+  typedef mozilla::gfx::SamplingFilter SamplingFilter;
+  typedef mozilla::gfx::Float Float;
+  typedef mozilla::gfx::Point Point;
+  typedef mozilla::gfx::Rect Rect;
+  typedef mozilla::gfx::RectDouble RectDouble;
+  typedef mozilla::gfx::Size Size;
+  typedef mozilla::gfx::Matrix4x4 Matrix4x4;
+  typedef mozilla::gfx::Matrix4x4Flagged Matrix4x4Flagged;
+  typedef mozilla::gfx::MatrixScales MatrixScales;
+  typedef mozilla::gfx::MatrixScalesDouble MatrixScalesDouble;
+  typedef mozilla::gfx::RectCornerRadii RectCornerRadii;
+  typedef mozilla::gfx::StrokeOptions StrokeOptions;
+  typedef mozilla::image::ImgDrawResult ImgDrawResult;
+
+  using nsDisplayItem = mozilla::nsDisplayItem;
+  using nsDisplayList = mozilla::nsDisplayList;
+  using nsDisplayListBuilder = mozilla::nsDisplayListBuilder;
+  using nsDisplayListBuilderMode = mozilla::nsDisplayListBuilderMode;
+  using RetainedDisplayListBuilder = mozilla::RetainedDisplayListBuilder;
+
+ public:
+  typedef mozilla::layers::FrameMetrics FrameMetrics;
+  typedef mozilla::layers::ScrollMetadata ScrollMetadata;
+  typedef mozilla::layers::ScrollableLayerGuid::ViewID ViewID;
+  typedef mozilla::CSSPoint CSSPoint;
+  typedef mozilla::CSSSize CSSSize;
+  typedef mozilla::CSSIntSize CSSIntSize;
+  typedef mozilla::CSSRect CSSRect;
+  typedef mozilla::ScreenMargin ScreenMargin;
+  typedef mozilla::LayoutDeviceIntSize LayoutDeviceIntSize;
+  typedef mozilla::LayoutDeviceRect LayoutDeviceRect;
+  typedef mozilla::PresShell PresShell;
+  typedef mozilla::StyleGeometryBox StyleGeometryBox;
+  typedef mozilla::SVGImageContext SVGImageContext;
+  typedef mozilla::LogicalSize LogicalSize;
+
+  /**
+   * Finds previously assigned ViewID for the given content element, if any.
+   * Returns whether a ViewID was previously assigned.
+   */
+  static bool FindIDFor(const nsIContent* aContent, ViewID* aOutViewId);
+
+  /**
+   * Finds previously assigned or generates a unique ViewID for the given
+   * content element.
+   */
+  static ViewID FindOrCreateIDFor(nsIContent* aContent);
+
+  /**
+   * Find content for given ID.
+   */
+  static nsIContent* FindContentFor(ViewID aId);
+
+  /**
+   * Find the scrollable frame for a given content element.
+   */
+  static nsIScrollableFrame* FindScrollableFrameFor(nsIContent* aContent);
+
+  /**
+   * Find the scrollable frame for a given ID.
+   */
+  static nsIScrollableFrame* FindScrollableFrameFor(ViewID aId);
+
+  /**
+   * Helper for FindScrollableFrameFor(), also used in DisplayPortUtils.
+   * Most clients should use FindScrollableFrameFor().
+   */
+  static nsIFrame* GetScrollFrameFromContent(nsIContent* aContent);
+
+  /**
+   * Find the ID for a given scrollable frame.
+   */
+  static ViewID FindIDForScrollableFrame(nsIScrollableFrame* aScrollable);
+
+  /**
+   * Notify the scroll frame with the given scroll id that its scroll offset
+   * is being sent to APZ as part of a paint-skip transaction.
+   *
+   * Normally, this notification happens during painting, after calls to
+   * ComputeScrollMetadata(). During paint-skipping that code is skipped,
+   * but it's still important for the scroll frame to be notified for
+   * correctness of relative scroll updates, so the code that sends the
+   * empty paint-skip transaction needs to call this.
+   */
+  static void NotifyPaintSkipTransaction(ViewID aScrollId);
+
+  /**
+   * Use heuristics to figure out the child list that
+   * aChildFrame is currently in.
+   */
+  static mozilla::FrameChildListID GetChildListNameFor(nsIFrame* aChildFrame);
+
+  /**
+   * Returns the ::before pseudo-element for aContent, if any.
+   */
+  static mozilla::dom::Element* GetBeforePseudo(const nsIContent* aContent);
+
+  /**
+   * Returns the frame corresponding to the ::before pseudo-element for
+   * aContent, if any.
+   */
+  static nsIFrame* GetBeforeFrame(const nsIContent* aContent);
+
+  /**
+   * Returns the ::after pseudo-element for aContent, if any.
+   */
+  static mozilla::dom::Element* GetAfterPseudo(const nsIContent* aContent);
+
+  /**
+   * Returns the frame corresponding to the ::after pseudo-element for aContent,
+   * if any.
+   */
+  static nsIFrame* GetAfterFrame(const nsIContent* aContent);
+
+  /**
+   * Returns the ::marker pseudo-element for aContent, if any.
+   */
+  static mozilla::dom::Element* GetMarkerPseudo(const nsIContent* aContent);
+
+  /**
+   * Returns the frame corresponding to the ::marker pseudo-element for
+   * aContent, if any.
+   */
+  static nsIFrame* GetMarkerFrame(const nsIContent* aContent);
+
+#ifdef ACCESSIBILITY
+  /**
+   * Set aText to the spoken text for the given ::marker content (aContent)
+   * if it has a frame, or the empty string otherwise.
+   */
+  static void GetMarkerSpokenText(const nsIContent* aContent, nsAString& aText);
+#endif
+
+  /**
+   * Given a frame, search up the frame tree until we find an
+   * ancestor that (or the frame itself) is of type aFrameType, if any.
+   *
+   * @param aFrame the frame to start at
+   * @param aFrameType the frame type to look for
+   * @param aStopAt a frame to stop at after we checked it
+   * @return a frame of the given type or nullptr if no
+   *         such ancestor exists
+   */
+  static nsIFrame* GetClosestFrameOfType(nsIFrame* aFrame,
+                                         mozilla::LayoutFrameType aFrameType,
+                                         nsIFrame* aStopAt = nullptr);
+
+  /**
+   * Given a frame, search up the frame tree until we find an
+   * ancestor that (or the frame itself) is a "Page" frame, if any.
+   *
+   * @param aFrame the frame to start at
+   * @return a frame of type mozilla::LayoutFrameType::Page or nullptr if no
+   *         such ancestor exists
+   */
+  static nsIFrame* GetPageFrame(nsIFrame* aFrame);
+
+  /**
+   * Given a frame which is the primary frame for an element,
+   * return the frame that has the non-pseudoelement ComputedStyle for
+   * the content.
+   * This is aPrimaryFrame itself except for tableWrapper frames.
+   *
+   * Given a non-null input, this will return null if and only if its
+   * argument is a table wrapper frame that is mid-destruction (and its
+   * table frame has been destroyed).
+   */
+  static nsIFrame* GetStyleFrame(nsIFrame* aPrimaryFrame);
+  static const nsIFrame* GetStyleFrame(const nsIFrame* aPrimaryFrame);
+
+  /**
+   * Given a content node,
+   * return the frame that has the non-pseudoelement ComputedStyle for
+   * the content.  May return null.
+   * This is aContent->GetPrimaryFrame() except for tableWrapper frames.
+   */
+  static nsIFrame* GetStyleFrame(const nsIContent* aContent);
+
+  /**
+   * Returns the placeholder size for when the scrollbar is unthemed.
+   */
+  static mozilla::CSSIntCoord UnthemedScrollbarSize(
+      mozilla::StyleScrollbarWidth);
+
+  /**
+   * The inverse of GetStyleFrame. Returns |aStyleFrame| unless it is an inner
+   * table frame, in which case the table wrapper frame is returned.
+   */
+  static nsIFrame* GetPrimaryFrameFromStyleFrame(nsIFrame* aStyleFrame);
+  static const nsIFrame* GetPrimaryFrameFromStyleFrame(
+      const nsIFrame* aStyleFrame);
+
+  /**
+   * Similar to nsIFrame::IsPrimaryFrame except that this will return true
+   * for the inner table frame rather than for its wrapper frame.
+   */
+  static bool IsPrimaryStyleFrame(const nsIFrame* aFrame);
+
+#ifdef DEBUG
+  // TODO: remove, see bug 598468.
+  static bool gPreventAssertInCompareTreePosition;
+#endif  // DEBUG
+
+  /**
+   * CompareTreePosition determines whether aContent1 comes before or
+   * after aContent2 in a preorder traversal of the content tree.
+   *
+   * @param aCommonAncestor either null, or a common ancestor of
+   *                        aContent1 and aContent2.  Actually this is
+   *                        only a hint; if it's not an ancestor of
+   *                        aContent1 or aContent2, this function will
+   *                        still work, but it will be slower than
+   *                        normal.
+   * @return < 0 if aContent1 is before aContent2
+   *         > 0 if aContent1 is after aContent2,
+   *         0 otherwise (meaning they're the same, or they're in
+   *           different documents)
+   */
+  static int32_t CompareTreePosition(
+      nsIContent* aContent1, nsIContent* aContent2,
+      const nsIContent* aCommonAncestor = nullptr) {
+    return DoCompareTreePosition(aContent1, aContent2, -1, 1, aCommonAncestor);
+  }
+
+  /*
+   * More generic version of |CompareTreePosition|.  |aIf1Ancestor|
+   * gives the value to return when 1 is an ancestor of 2, and likewise
+   * for |aIf2Ancestor|.  Passing (-1, 1) gives preorder traversal
+   * order, and (1, -1) gives postorder traversal order.
+   */
+  static int32_t DoCompareTreePosition(
+      nsIContent* aContent1, nsIContent* aContent2, int32_t aIf1Ancestor,
+      int32_t aIf2Ancestor, const nsIContent* aCommonAncestor = nullptr);
+
+  /**
+   * CompareTreePosition determines whether aFrame1 comes before or
+   * after aFrame2 in a preorder traversal of the frame tree, where out
+   * of flow frames are treated as children of their placeholders. This is
+   * basically the same ordering as DoCompareTreePosition(nsIContent*) except
+   * that it handles anonymous content properly and there are subtleties with
+   * continuations.
+   *
+   * @param aCommonAncestor either null, or a common ancestor of
+   *                        aContent1 and aContent2.  Actually this is
+   *                        only a hint; if it's not an ancestor of
+   *                        aContent1 or aContent2, this function will
+   *                        still work, but it will be slower than
+   *                        normal.
+   * @return < 0 if aContent1 is before aContent2
+   *         > 0 if aContent1 is after aContent2,
+   *         0 otherwise (meaning they're the same, or they're in
+   *           different frame trees)
+   */
+  static int32_t CompareTreePosition(nsIFrame* aFrame1, nsIFrame* aFrame2,
+                                     nsIFrame* aCommonAncestor = nullptr) {
+    return DoCompareTreePosition(aFrame1, aFrame2, -1, 1, aCommonAncestor);
+  }
+
+  static int32_t CompareTreePosition(nsIFrame* aFrame1, nsIFrame* aFrame2,
+                                     nsTArray<nsIFrame*>& aFrame2Ancestors,
+                                     nsIFrame* aCommonAncestor = nullptr) {
+    return DoCompareTreePosition(aFrame1, aFrame2, aFrame2Ancestors, -1, 1,
+                                 aCommonAncestor);
+  }
+
+  /*
+   * More generic version of |CompareTreePosition|.  |aIf1Ancestor|
+   * gives the value to return when 1 is an ancestor of 2, and likewise
+   * for |aIf2Ancestor|.  Passing (-1, 1) gives preorder traversal
+   * order, and (1, -1) gives postorder traversal order.
+   */
+  static int32_t DoCompareTreePosition(nsIFrame* aFrame1, nsIFrame* aFrame2,
+                                       int32_t aIf1Ancestor,
+                                       int32_t aIf2Ancestor,
+                                       nsIFrame* aCommonAncestor = nullptr);
+
+  static nsIFrame* FillAncestors(nsIFrame* aFrame, nsIFrame* aStopAtAncestor,
+                                 nsTArray<nsIFrame*>* aAncestors);
+
+  static int32_t DoCompareTreePosition(nsIFrame* aFrame1, nsIFrame* aFrame2,
+                                       nsTArray<nsIFrame*>& aFrame2Ancestors,
+                                       int32_t aIf1Ancestor,
+                                       int32_t aIf2Ancestor,
+                                       nsIFrame* aCommonAncestor);
+
+  /**
+   * LastContinuationWithChild gets the last continuation in aFrame's chain
+   * that has a child, or the first continuation if the frame has no children.
+   */
+  static nsContainerFrame* LastContinuationWithChild(nsContainerFrame* aFrame);
+
+  /**
+   * GetLastSibling simply finds the last sibling of aFrame, or returns nullptr
+   * if aFrame is null.
+   */
+  static nsIFrame* GetLastSibling(nsIFrame* aFrame);
+
+  /**
+   * FindSiblingViewFor locates the child of aParentView that aFrame's
+   * view should be inserted 'above' (i.e., before in sibling view
+   * order).  This is the first child view of aParentView whose
+   * corresponding content is before aFrame's content (view siblings
+   * are in reverse content order).
+   */
+  static nsView* FindSiblingViewFor(nsView* aParentView, nsIFrame* aFrame);
+
+  /**
+   * Get the parent of aFrame. If aFrame is the root frame for a document,
+   * and the document has a parent document in the same view hierarchy, then
+   * we try to return the subdocumentframe in the parent document.
+   * @param aCrossDocOffset [in/out] if non-null, then as we cross documents
+   * an extra offset may be required and it will be added to aCrossDocOffset.
+   * Be careful dealing with this extra offset as it is in app units of the
+   * parent document, which may have a different app units per dev pixel ratio
+   * than the child document.
+   * Note that, while this function crosses document boundaries, it (naturally)
+   * cannot cross process boundaries.
+   */
+  static nsIFrame* GetCrossDocParentFrameInProcess(
+      const nsIFrame* aFrame, nsPoint* aCrossDocOffset = nullptr);
+
+  /**
+   * Does the same thing as GetCrossDocParentFrameInProcess().
+   * The purpose of having two functions is to more easily track which call
+   * sites have been audited to consider out-of-process iframes (bug 1599913).
+   * Once all call sites have been audited, this function can be removed.
+   */
+  static nsIFrame* GetCrossDocParentFrame(const nsIFrame* aFrame,
+                                          nsPoint* aCrossDocOffset = nullptr);
+
+  /**
+   * IsProperAncestorFrame checks whether aAncestorFrame is an ancestor
+   * of aFrame and not equal to aFrame.
+   * @param aCommonAncestor nullptr, or a common ancestor of aFrame and
+   * aAncestorFrame. If non-null, this can bound the search and speed up
+   * the function
+   */
+  static bool IsProperAncestorFrame(const nsIFrame* aAncestorFrame,
+                                    const nsIFrame* aFrame,
+                                    const nsIFrame* aCommonAncestor = nullptr);
+
+  /**
+   * Like IsProperAncestorFrame, but looks across document boundaries.
+   *
+   * Just like IsAncestorFrameCrossDoc, except that it returns false when
+   * aFrame == aAncestorFrame.
+   * TODO: Once after we fixed bug 1715932, this function should be removed.
+   */
+  static bool IsProperAncestorFrameCrossDoc(
+      const nsIFrame* aAncestorFrame, const nsIFrame* aFrame,
+      const nsIFrame* aCommonAncestor = nullptr);
+
+  /**
+   * Like IsProperAncestorFrame, but looks across document boundaries.
+   *
+   * Just like IsAncestorFrameCrossDoc, except that it returns false when
+   * aFrame == aAncestorFrame.
+   */
+  static bool IsProperAncestorFrameCrossDocInProcess(
+      const nsIFrame* aAncestorFrame, const nsIFrame* aFrame,
+      const nsIFrame* aCommonAncestor = nullptr);
+
+  /**
+   * IsAncestorFrameCrossDoc checks whether aAncestorFrame is an ancestor
+   * of aFrame or equal to aFrame, looking across document boundaries.
+   * @param aCommonAncestor nullptr, or a common ancestor of aFrame and
+   * aAncestorFrame. If non-null, this can bound the search and speed up
+   * the function.
+   *
+   * Just like IsProperAncestorFrameCrossDoc, except that it returns true when
+   * aFrame == aAncestorFrame.
+   *
+   * TODO: Bug 1700245, all call sites of this function will be eventually
+   * replaced by IsAncestorFrameCrossDocInProcess.
+   */
+  static bool IsAncestorFrameCrossDoc(
+      const nsIFrame* aAncestorFrame, const nsIFrame* aFrame,
+      const nsIFrame* aCommonAncestor = nullptr);
+
+  /**
+   * IsAncestorFrameCrossDocInProcess checks whether aAncestorFrame is an
+   * ancestor of aFrame or equal to aFrame, looking across document boundaries
+   * in the same process.
+   * @param aCommonAncestor nullptr, or a common ancestor of aFrame and
+   * aAncestorFrame. If non-null, this can bound the search and speed up
+   * the function.
+   *
+   * Just like IsProperAncestorFrameCrossDoc, except that it returns true when
+   * aFrame == aAncestorFrame.
+   *
+   * NOTE: This function doesn't return true even if |aAncestorFrame| and
+   * |aFrame| is in the same process but they are not directly connected, e.g.
+   * both |aAncestorFrame| and |aFrame| in A domain documents, but there's
+   * another an iframe document domain B, such as A1 -> B1 ->A2 document tree.
+   */
+  static bool IsAncestorFrameCrossDocInProcess(
+      const nsIFrame* aAncestorFrame, const nsIFrame* aFrame,
+      const nsIFrame* aCommonAncestor = nullptr);
+
+  static mozilla::SideBits GetSideBitsForFixedPositionContent(
+      const nsIFrame* aFixedPosFrame);
+
+  /**
+   * Get the scroll id for the root scrollframe of the presshell of the given
+   * prescontext. Returns NULL_SCROLL_ID if it couldn't be found.
+   */
+  static ViewID ScrollIdForRootScrollFrame(nsPresContext* aPresContext);
+
+  /**
+   * GetScrollableFrameFor returns the scrollable frame for a scrolled frame
+   */
+  static nsIScrollableFrame* GetScrollableFrameFor(
+      const nsIFrame* aScrolledFrame);
+
+  /**
+   * GetNearestScrollableFrameForDirection locates the first ancestor of
+   * aFrame (or aFrame itself) that is scrollable with overflow:scroll or
+   * overflow:auto in the given direction and where either the scrollbar for
+   * that direction is visible or the frame can be scrolled by some
+   * positive amount in that direction.
+   * The search extends across document boundaries.
+   *
+   * @param  aFrame the frame to start with
+   * @param  aDirection Whether it's for horizontal or vertical scrolling.
+   * @return the nearest scrollable frame or nullptr if not found
+   */
+  static nsIScrollableFrame* GetNearestScrollableFrameForDirection(
+      nsIFrame* aFrame, mozilla::layers::ScrollDirections aDirections);
+
+  enum {
+    /**
+     * If the SCROLLABLE_SAME_DOC flag is set, then we only walk the frame tree
+     * up to the root frame in the current document.
+     */
+    SCROLLABLE_SAME_DOC = 0x01,
+    /**
+     * If the SCROLLABLE_INCLUDE_HIDDEN flag is set then we allow
+     * overflow:hidden scrollframes to be returned as scrollable frames.
+     */
+    SCROLLABLE_INCLUDE_HIDDEN = 0x02,
+    /**
+     * If the SCROLLABLE_ONLY_ASYNC_SCROLLABLE flag is set, then we only
+     * want to match scrollable frames for which WantAsyncScroll() returns
+     * true.
+     */
+    SCROLLABLE_ONLY_ASYNC_SCROLLABLE = 0x04,
+    /**
+     * If the SCROLLABLE_ALWAYS_MATCH_ROOT flag is set, then we will always
+     * return the root scrollable frame for the root document (in the current
+     * process) if we encounter it, whether or not it is async scrollable or
+     * overflow: hidden.
+     */
+    SCROLLABLE_ALWAYS_MATCH_ROOT = 0x08,
+    /**
+     * If the SCROLLABLE_FIXEDPOS_FINDS_ROOT flag is set, then for fixed-pos
+     * frames return the root scrollable frame for that document.
+     */
+    SCROLLABLE_FIXEDPOS_FINDS_ROOT = 0x10,
+    /**
+     * If the SCROLLABLE_STOP_AT_PAGE flag is set, then we stop searching
+     * for scrollable ancestors when seeing a nsPageFrame.  This can be used
+     * to avoid finding the viewport scroll frame in Print Preview (which
+     * would be undesirable as a 'position:sticky' container for content).
+     */
+    SCROLLABLE_STOP_AT_PAGE = 0x20,
+  };
+  /**
+   * GetNearestScrollableFrame locates the first ancestor of aFrame
+   * (or aFrame itself) that is scrollable with overflow:scroll or
+   * overflow:auto in some direction.
+   *
+   * @param  aFrame the frame to start with
+   * @param  aFlags if SCROLLABLE_SAME_DOC is set, do not search across
+   * document boundaries. If SCROLLABLE_INCLUDE_HIDDEN is set, include
+   * frames scrollable with overflow:hidden.
+   * @return the nearest scrollable frame or nullptr if not found
+   */
+  static nsIScrollableFrame* GetNearestScrollableFrame(nsIFrame* aFrame,
+                                                       uint32_t aFlags = 0);
+
+  /**
+   * GetScrolledRect returns the range of allowable scroll offsets
+   * for aScrolledFrame, assuming the scrollable overflow area is
+   * aScrolledFrameOverflowArea and the scrollport size is aScrollPortSize.
+   */
+  static nsRect GetScrolledRect(nsIFrame* aScrolledFrame,
+                                const nsRect& aScrolledFrameOverflowArea,
+                                const nsSize& aScrollPortSize,
+                                mozilla::StyleDirection);
+
+  /**
+   * HasPseudoStyle returns true if aContent (whose primary style
+   * context is aComputedStyle) has the aPseudoElement pseudo-style
+   * attached to it; returns false otherwise.
+   *
+   * @param aContent the content node we're looking at
+   * @param aComputedStyle aContent's ComputedStyle
+   * @param aPseudoElement the id of the pseudo style we care about
+   * @param aPresContext the presentation context
+   * @return whether aContent has aPseudoElement style attached to it
+   */
+  static bool HasPseudoStyle(nsIContent* aContent,
+                             ComputedStyle* aComputedStyle,
+                             mozilla::PseudoStyleType aPseudoElement,
+                             nsPresContext* aPresContext);
+
+  /**
+   * If this frame is a placeholder for a float, then return the float,
+   * otherwise return nullptr.  aPlaceholder must be a placeholder frame.
+   */
+  static nsIFrame* GetFloatFromPlaceholder(nsIFrame* aPlaceholder);
+
+  // Combine aOrigClearType with aNewClearType, but limit the clear types
+  // to StyleClear::Left, Right, Both.
+  static mozilla::StyleClear CombineClearType(
+      mozilla::StyleClear aOrigClearType, mozilla::StyleClear aNewClearType);
+
+  /**
+   * Get the coordinates of a given DOM mouse event, relative to a given
+   * frame. Works only for DOM events generated by WidgetGUIEvents.
+   * @param aDOMEvent the event
+   * @param aFrame the frame to make coordinates relative to
+   * @return the point, or (NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE) if
+   * for some reason the coordinates for the mouse are not known (e.g.,
+   * the event is not a GUI event).
+   */
+  static nsPoint GetDOMEventCoordinatesRelativeTo(
+      mozilla::dom::Event* aDOMEvent, nsIFrame* aFrame);
+
+  /**
+   * Get the coordinates of a given native mouse event, relative to a given
+   * frame.
+   * @param aEvent the event
+   * @param aFrame the frame to make coordinates relative to
+   * @return the point, or (NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE) if
+   * for some reason the coordinates for the mouse are not known (e.g.,
+   * the event is not a GUI event).
+   */
+  static nsPoint GetEventCoordinatesRelativeTo(
+      const mozilla::WidgetEvent* aEvent, RelativeTo aFrame);
+
+  /**
+   * Get the coordinates of a given point relative to an event and a
+   * given frame.
+   * @param aEvent the event
+   * @param aPoint the point to get the coordinates relative to
+   * @param aFrame the frame to make coordinates relative to
+   * @return the point, or (NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE) if
+   * for some reason the coordinates for the mouse are not known (e.g.,
+   * the event is not a GUI event).
+   */
+  static nsPoint GetEventCoordinatesRelativeTo(
+      const mozilla::WidgetEvent* aEvent,
+      const mozilla::LayoutDeviceIntPoint& aPoint, RelativeTo aFrame);
+
+  /**
+   * Get the coordinates of a given point relative to a widget and a
+   * given frame.
+   * @param aWidget the event src widget
+   * @param aPoint the point to get the coordinates relative to
+   * @param aFrame the frame to make coordinates relative to
+   * @return the point, or (NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE) if
+   * for some reason the coordinates for the mouse are not known (e.g.,
+   * the event is not a GUI event).
+   */
+  static nsPoint GetEventCoordinatesRelativeTo(
+      nsIWidget* aWidget, const mozilla::LayoutDeviceIntPoint& aPoint,
+      RelativeTo aFrame);
+
+  /**
+   * Get the popup frame of a given native mouse event.
+   * @param aRootPresContext only check popups within aRootPresContext or a
+   * descendant
+   * @param aEvent  the event.
+   * @return        Null, if there is no popup frame at the point, otherwise,
+   *                returns top-most popup frame at the point.
+   */
+  static nsIFrame* GetPopupFrameForEventCoordinates(
+      nsPresContext* aRootPresContext, const mozilla::WidgetEvent* aEvent);
+
+  /**
+   * Get the popup frame of a given point relative to a widget.
+   * @param aRootPresContext only check popups within aRootPresContext or a
+   * descendant
+   * @param aEvent  the event.
+   * @return        Null, if there is no popup frame at the point, otherwise,
+   *                returns top-most popup frame at the point.
+   */
+  enum class GetPopupFrameForPointFlags : uint8_t {
+    OnlyReturnFramesWithWidgets = 0x1,
+  };
+  static nsIFrame* GetPopupFrameForPoint(
+      nsPresContext* aRootPresContext, nsIWidget* aWidget,
+      const mozilla::LayoutDeviceIntPoint& aPoint,
+      GetPopupFrameForPointFlags aFlags = GetPopupFrameForPointFlags(0));
+
+  /**
+   * Get container and offset if aEvent collapses Selection.
+   * @param aPresShell      The PresShell handling aEvent.
+   * @param aEvent          The event having coordinates where you want to
+   *                        collapse Selection.
+   * @param aContainer      Returns the container node at the point.
+   *                        Set nullptr if you don't need this.
+   * @param aOffset         Returns offset in the container node at the point.
+   *                        Set nullptr if you don't need this.
+   */
+  MOZ_CAN_RUN_SCRIPT
+  static void GetContainerAndOffsetAtEvent(PresShell* aPresShell,
+                                           const mozilla::WidgetEvent* aEvent,
+                                           nsIContent** aContainer,
+                                           int32_t* aOffset);
+
+  /**
+   * Translate from widget coordinates to the view's coordinates
+   * @param aPresContext the PresContext for the view
+   * @param aWidget the widget
+   * @param aPt the point relative to the widget
+   * @param aView  view to which returned coordinates are relative
+   * @return the point in the view's coordinates
+   */
+  static nsPoint TranslateWidgetToView(nsPresContext* aPresContext,
+                                       nsIWidget* aWidget,
+                                       const mozilla::LayoutDeviceIntPoint& aPt,
+                                       nsView* aView);
+
+  /**
+   * Translate from view coordinates to the widget's coordinates.
+   * @param aPresContext the PresContext for the view
+   * @param aView the view
+   * @param aPt the point relative to the view
+   * @param aViewportType whether the point is in visual or layout coordinates
+   * @param aWidget the widget to which returned coordinates are relative
+   * @return the point in the view's coordinates
+   */
+  static mozilla::LayoutDeviceIntPoint TranslateViewToWidget(
+      nsPresContext* aPresContext, nsView* aView, nsPoint aPt,
+      ViewportType aViewportType, nsIWidget* aWidget);
+
+  static mozilla::LayoutDeviceIntPoint WidgetToWidgetOffset(
+      nsIWidget* aFromWidget, nsIWidget* aToWidget);
+
+  enum class FrameForPointOption {
+    /**
+     * When set, paint suppression is ignored, so we'll return non-root page
+     * elements even if paint suppression is stopping them from painting.
+     */
+    IgnorePaintSuppression = 1,
+    /**
+     * When set, clipping due to the root scroll frame (and any other viewport-
+     * related clipping) is ignored.
+     */
+    IgnoreRootScrollFrame,
+    /**
+     * When set, return only content in the same document as aFrame.
+     */
+    IgnoreCrossDoc,
+    /**
+     * When set, return only content that is actually visible.
+     */
+    OnlyVisible,
+  };
+
+  struct FrameForPointOptions {
+    using Bits = mozilla::EnumSet<FrameForPointOption>;
+
+    Bits mBits;
+    // If mBits contains OnlyVisible, what is the opacity threshold which we
+    // consider "opaque enough" to clobber stuff underneath.
+    float mVisibleThreshold;
+
+    FrameForPointOptions(Bits aBits, float aVisibleThreshold)
+        : mBits(aBits), mVisibleThreshold(aVisibleThreshold){};
+
+    MOZ_IMPLICIT FrameForPointOptions(Bits aBits)
+        : FrameForPointOptions(aBits, 1.0f) {}
+
+    FrameForPointOptions() : FrameForPointOptions(Bits()){};
+  };
+
+  /**
+   * Given aFrame, the root frame of a stacking context, find its descendant
+   * frame under the point aPt that receives a mouse event at that location,
+   * or nullptr if there is no such frame.
+   * @param aPt the point, relative to the frame origin, in either visual
+   *            or layout coordinates depending on aRelativeTo.mViewportType
+   */
+  static nsIFrame* GetFrameForPoint(RelativeTo aRelativeTo, nsPoint aPt,
+                                    const FrameForPointOptions& = {});
+
+  /**
+   * Given aFrame, the root frame of a stacking context, find all descendant
+   * frames under the area of a rectangle that receives a mouse event,
+   * or nullptr if there is no such frame.
+   * @param aRect the rect, relative to the frame origin, in either visual
+   *              or layout coordinates depending on aRelativeTo.mViewportType
+   * @param aOutFrames an array to add all the frames found
+   */
+  static nsresult GetFramesForArea(RelativeTo aRelativeTo, const nsRect& aRect,
+                                   nsTArray<nsIFrame*>& aOutFrames,
+                                   const FrameForPointOptions& = {});
+
+  /**
+   * Transform aRect relative to aFrame up to the coordinate system of
+   * aAncestor. Computes the bounding-box of the true quadrilateral.
+   * Pass non-null aPreservesAxisAlignedRectangles and it will be set to true if
+   * we only need to use a 2d transform that PreservesAxisAlignedRectangles().
+   * The corner positions of aRect are treated as meaningful even if aRect is
+   * empty.
+   *
+   * |aMatrixCache| allows for optimizations in recomputing the same matrix over
+   * and over. The argument can be one of the following values:
+   *
+   * nullptr (the default) - No optimization; the transform matrix is computed
+   * on every call to this function.
+   *
+   * non-null pointer to an empty Maybe<Matrix4x4> - Upon return, the Maybe is
+   * filled with the transform matrix that was computed. This can then be passed
+   * in to subsequent calls with the same source and destination frames to avoid
+   * recomputing the matrix.
+   *
+   * non-null pointer to a non-empty Matrix4x4 - The provided matrix will be
+   * used as the transform matrix and applied to the rect.
+   */
+  static nsRect TransformFrameRectToAncestor(
+      const nsIFrame* aFrame, const nsRect& aRect, const nsIFrame* aAncestor,
+      bool* aPreservesAxisAlignedRectangles = nullptr,
+      mozilla::Maybe<Matrix4x4Flagged>* aMatrixCache = nullptr,
+      bool aStopAtStackingContextAndDisplayPortAndOOFFrame = false,
+      nsIFrame** aOutAncestor = nullptr) {
+    return TransformFrameRectToAncestor(
+        aFrame, aRect, RelativeTo{aAncestor}, aPreservesAxisAlignedRectangles,
+        aMatrixCache, aStopAtStackingContextAndDisplayPortAndOOFFrame,
+        aOutAncestor);
+  }
+  static nsRect TransformFrameRectToAncestor(
+      const nsIFrame* aFrame, const nsRect& aRect, RelativeTo aAncestor,
+      bool* aPreservesAxisAlignedRectangles = nullptr,
+      mozilla::Maybe<Matrix4x4Flagged>* aMatrixCache = nullptr,
+      bool aStopAtStackingContextAndDisplayPortAndOOFFrame = false,
+      nsIFrame** aOutAncestor = nullptr);
+
+  /**
+   * Gets the transform for aFrame relative to aAncestor. Pass null for
+   * aAncestor to go up to the root frame. Including nsIFrame::IN_CSS_UNITS
+   * flag in aFlags will return CSS pixels, by default it returns device
+   * pixels.
+   * More info can be found in nsIFrame::GetTransformMatrix.
+   *
+   * Some notes on the possible combinations of |aFrame.mViewportType| and
+   * |aAncestor.mViewportType|:
+   *
+   * | aFrame.       | aAncestor.    | Notes
+   * | mViewportType | mViewportType |
+   * ==========================================================================
+   * | Layout        | Layout        | Commonplace, when both source and target
+   * |               |               | are inside zoom boundary.
+   * |               |               |
+   * |               |               | Could also happen in non-e10s setups
+   * |               |               | when both source and target are outside
+   * |               |               | the zoom boundary and the code is
+   * |               |               | oblivious to the existence of a zoom
+   * |               |               | boundary.
+   * ==========================================================================
+   * | Layout        | Visual        | Commonplace, used when hit testing visual
+   * |               |               | coordinates (e.g. coming from user input
+   * |               |               | events). We expected to encounter a
+   * |               |               | zoomed content root during traversal and
+   * |               |               | apply a layout-to-visual transform.
+   * ==========================================================================
+   * | Visual        | Layout        | Should never happen, will assert.
+   * ==========================================================================
+   * | Visual        | Visual        | In e10s setups, should only happen if
+   * |               |               | aFrame and aAncestor are both the
+   * |               |               | RCD viewport frame.
+   * |               |               |
+   * |               |               | In non-e10s setups, could happen with
+   * |               |               | different frames if they are both
+   * |               |               | outside the zoom boundary.
+   * ==========================================================================
+   */
+  static Matrix4x4Flagged GetTransformToAncestor(
+      RelativeTo aFrame, RelativeTo aAncestor, uint32_t aFlags = 0,
+      nsIFrame** aOutAncestor = nullptr);
+
+  /**
+   * Gets the scale factors of the transform for aFrame relative to the root
+   * frame if this transform can be drawn 2D, or the identity scale factors
+   * otherwise.
+   */
+  static MatrixScales GetTransformToAncestorScale(const nsIFrame* aFrame);
+
+  /**
+   * Gets the scale factors of the transform for aFrame relative to the root
+   * frame if this transform is 2D, or the identity scale factors otherwise.
+   * If some frame on the path from aFrame to the display root frame may have an
+   * animated scale, returns the identity scale factors.
+   */
+  static MatrixScales GetTransformToAncestorScaleExcludingAnimated(
+      nsIFrame* aFrame);
+
+  /**
+   * Gets a scale that includes CSS transforms in this process as well as the
+   * transform to ancestor scale passed down from our direct ancestor process
+   * (which includes any enclosing CSS transforms and resolution). Note: this
+   * does not include any resolution in the current process (this is on purpose
+   * because that is what the transform to ancestor field on FrameMetrics needs,
+   * see its definition for explanation as to why). This is the transform to
+   * ancestor scale to set on FrameMetrics.
+   */
+  static mozilla::ParentLayerToScreenScale2D
+  GetTransformToAncestorScaleCrossProcessForFrameMetrics(
+      const nsIFrame* aFrame);
+
+  /**
+   * Find the nearest common ancestor frame for aFrame1 and aFrame2. The
+   * ancestor frame could be cross-doc.
+   */
+  static const nsIFrame* FindNearestCommonAncestorFrame(
+      const nsIFrame* aFrame1, const nsIFrame* aFrame2);
+
+  /**
+   * Find the nearest common ancestor frame for aFrame1 and aFrame2, assuming
+   * that they are within the same block.
+   *
+   * Returns null if they are not within the same block.
+   */
+  static const nsIFrame* FindNearestCommonAncestorFrameWithinBlock(
+      const nsTextFrame* aFrame1, const nsTextFrame* aFrame2);
+
+  /**
+   * Whether author-specified borders / backgrounds disable theming for a given
+   * appearance value.
+   */
+  static bool AuthorSpecifiedBorderBackgroundDisablesTheming(
+      mozilla::StyleAppearance);
+
+  /**
+   * Transforms a list of CSSPoints from aFromFrame to aToFrame, taking into
+   * account all relevant transformations on the frames up to (but excluding)
+   * their nearest common ancestor.
+   * If we encounter a transform that we need to invert but which is
+   * non-invertible, we return NONINVERTIBLE_TRANSFORM. If the frames have
+   * no common ancestor, we return NO_COMMON_ANCESTOR.
+   * If this returns TRANSFORM_SUCCEEDED, the points in aPoints are transformed
+   * in-place, otherwise they are untouched.
+   */
+  enum TransformResult {
+    TRANSFORM_SUCCEEDED,
+    NO_COMMON_ANCESTOR,
+    NONINVERTIBLE_TRANSFORM
+  };
+  static TransformResult TransformPoints(RelativeTo aFromFrame,
+                                         RelativeTo aToFrame,
+                                         uint32_t aPointCount,
+                                         CSSPoint* aPoints);
+
+  /**
+   * Same as above function, but transform points in app units and
+   * handle 1 point per call.
+   */
+  static TransformResult TransformPoint(RelativeTo aFromFrame,
+                                        RelativeTo aToFrame, nsPoint& aPoint);
+
+  /**
+   * Transforms a rect from aFromFrame to aToFrame. In app units.
+   * Returns the bounds of the actual rect if the transform requires rotation
+   * or anything complex like that.
+   */
+  static TransformResult TransformRect(const nsIFrame* aFromFrame,
+                                       const nsIFrame* aToFrame, nsRect& aRect);
+
+  /**
+   * Converts app units to pixels (with optional snapping) and appends as a
+   * translation to aTransform.
+   */
+  static void PostTranslate(Matrix4x4& aTransform, const nsPoint& aOrigin,
+                            float aAppUnitsPerPixel, bool aRounded);
+
+  /*
+   * Whether the frame should snap to grid. This will end up being passed
+   * as the aRounded parameter in PostTranslate above. SVG frames should
+   * not have their translation rounded.
+   */
+  static bool ShouldSnapToGrid(const nsIFrame* aFrame);
+
+  /**
+   * Get the border-box of aElement's primary frame, transformed it to be
+   * relative to aFrame.
+   */
+  static nsRect GetRectRelativeToFrame(mozilla::dom::Element* aElement,
+                                       nsIFrame* aFrame);
+
+  /**
+   * Returns true if aRect with border inflation of size aInflateSize contains
+   * aPoint.
+   */
+  static bool ContainsPoint(const nsRect& aRect, const nsPoint& aPoint,
+                            nscoord aInflateSize);
+
+  /**
+   * Clamp aRect relative to aFrame to the scroll frames boundary searching from
+   * aFrame.
+   */
+  static nsRect ClampRectToScrollFrames(nsIFrame* aFrame, const nsRect& aRect);
+
+  /**
+   * Return true if a "layer transform" could be computed for aFrame,
+   * and optionally return the computed transform.  The returned
+   * transform is what would be set on the layer currently if a layers
+   * transaction were opened at the time this helper is called.
+   */
+  static bool GetLayerTransformForFrame(nsIFrame* aFrame,
+                                        Matrix4x4Flagged* aTransform);
+
+  /**
+   * Given a point in the global coordinate space, returns that point expressed
+   * in the coordinate system of aFrame.  This effectively inverts all
+   * transforms between this point and the root frame.
+   *
+   * @param aFromType Specifies whether |aPoint| is in layout or visual
+   * coordinates.
+   * @param aFrame The frame that acts as the coordinate space container.
+   * @param aPoint The point, in global layout or visual coordinates (as per
+   * |aFromType|, to get in the frame-local space.
+   * @return aPoint, expressed in aFrame's canonical coordinate space.
+   */
+  static nsPoint TransformRootPointToFrame(ViewportType aFromType,
+                                           RelativeTo aFrame,
+                                           const nsPoint& aPoint) {
+    return TransformAncestorPointToFrame(aFrame, aPoint,
+                                         RelativeTo{nullptr, aFromType});
+  }
+
+  /**
+   * Transform aPoint relative to aAncestor down to the coordinate system of
+   * aFrame.
+   */
+  static nsPoint TransformAncestorPointToFrame(RelativeTo aFrame,
+                                               const nsPoint& aPoint,
+                                               RelativeTo aAncestor);
+
+  /**
+   * Helper function that, given a rectangle and a matrix, returns the smallest
+   * rectangle containing the image of the source rectangle.
+   *
+   * @param aBounds The rectangle to transform.
+   * @param aMatrix The matrix to transform it with.
+   * @param aFactor The number of app units per graphics unit.
+   * @return The smallest rect that contains the image of aBounds.
+   */
+  static nsRect MatrixTransformRect(const nsRect& aBounds,
+                                    const Matrix4x4& aMatrix, float aFactor);
+  static nsRect MatrixTransformRect(const nsRect& aBounds,
+                                    const Matrix4x4Flagged& aMatrix,
+                                    float aFactor);
+
+  /**
+   * Helper function that, given a point and a matrix, returns the image
+   * of that point under the matrix transform.
+   *
+   * @param aPoint The point to transform.
+   * @param aMatrix The matrix to transform it with.
+   * @param aFactor The number of app units per graphics unit.
+   * @return The image of the point under the transform.
+   */
+  static nsPoint MatrixTransformPoint(const nsPoint& aPoint,
+                                      const Matrix4x4& aMatrix, float aFactor);
+
+  /**
+   * Given a graphics rectangle in graphics space, return a rectangle in
+   * app space that contains the graphics rectangle, rounding out as necessary.
+   *
+   * @param aRect The graphics rect to round outward.
+   * @param aFactor The number of app units per graphics unit.
+   * @return The smallest rectangle in app space that contains aRect.
+   */
+  template <typename T>
+  static nsRect RoundGfxRectToAppRect(const T& aRect, const float aFactor);
+
+  /**
+   * Returns a subrectangle of aContainedRect that is entirely inside the
+   * rounded rect. Complex cases are handled conservatively by returning a
+   * smaller rect than necessary.
+   */
+  static nsRegion RoundedRectIntersectRect(const nsRect& aRoundedRect,
+                                           const nscoord aRadii[8],
+                                           const nsRect& aContainedRect);
+  static nsIntRegion RoundedRectIntersectIntRect(
+      const nsIntRect& aRoundedRect, const RectCornerRadii& aCornerRadii,
+      const nsIntRect& aContainedRect);
+
+  /**
+   * Return whether any part of aTestRect is inside of the rounded
+   * rectangle formed by aBounds and aRadii (which are indexed by the
+   * enum HalfCorner constants in gfx/2d/Types.h). This is precise.
+   */
+  static bool RoundedRectIntersectsRect(const nsRect& aRoundedRect,
+                                        const nscoord aRadii[8],
+                                        const nsRect& aTestRect);
+
+  enum class PaintFrameFlags : uint32_t {
+    InTransform = 0x01,
+    SyncDecodeImages = 0x02,
+    WidgetLayers = 0x04,
+    IgnoreSuppression = 0x08,
+    DocumentRelative = 0x10,
+    HideCaret = 0x20,
+    ToWindow = 0x40,
+    ExistingTransaction = 0x80,
+    ForWebRender = 0x100,
+    UseHighQualityScaling = 0x200,
+    ResetViewportScrolling = 0x400,
+  };
+
+  /**
+   * Given aFrame, the root frame of a stacking context, paint it and its
+   * descendants to aRenderingContext.
+   * @param aRenderingContext a rendering context translated so that (0,0)
+   * is the origin of aFrame; for best results, (0,0) should transform
+   * to pixel-aligned coordinates. This can be null, in which case
+   * aFrame must be a "display root" (root frame for a root document,
+   * or the root of a popup) with an associated widget and we draw using
+   * the layer manager for the frame's widget.
+   * @param aDirtyRegion the region that must be painted, in the coordinates
+   * of aFrame.
+   * @param aBackstop paint the dirty area with this color before drawing
+   * the actual content; pass NS_RGBA(0,0,0,0) to draw no background.
+   * @param aBuilderMode Passed through to the display-list builder.
+   * @param aFlags if PAINT_IN_TRANSFORM is set, then we assume
+   * this is inside a transform or SVG foreignObject. If
+   * PAINT_SYNC_DECODE_IMAGES is set, we force synchronous decode on all
+   * images. If PAINT_WIDGET_LAYERS is set, aFrame must be a display root,
+   * and we will use the frame's widget's layer manager to paint
+   * even if aRenderingContext is non-null. This is useful if you want
+   * to force rendering to use the widget's layer manager for testing
+   * or speed. PAINT_WIDGET_LAYERS must be set if aRenderingContext is null.
+   * If PAINT_DOCUMENT_RELATIVE is used, the visible region is interpreted
+   * as being relative to the document (normally it's relative to the CSS
+   * viewport) and the document is painted as if no scrolling has occured.
+   * Only considered if PresShell::IgnoringViewportScrolling is true.
+   * If ResetViewportScrolling is used, then the root scroll frame's scroll
+   * position is set to 0 during painting, so that position:fixed elements
+   * are drawn in their initial position.
+   * PAINT_TO_WINDOW sets painting to window to true on the display list
+   * builder even if we can't tell that we are painting to the window.
+   * If PAINT_EXISTING_TRANSACTION is set, then BeginTransaction() has already
+   * been called on aFrame's widget's layer manager and should not be
+   * called again.
+   * If PAINT_COMPRESSED is set, the FrameLayerBuilder should be set to
+   * compressed mode to avoid short cut optimizations.
+   *
+   * So there are three possible behaviours:
+   * 1) PAINT_WIDGET_LAYERS is set and aRenderingContext is null; we paint
+   * by calling BeginTransaction on the widget's layer manager.
+   * 2) PAINT_WIDGET_LAYERS is set and aRenderingContext is non-null; we
+   * paint by calling BeginTransactionWithTarget on the widget's layer
+   * manager.
+   * 3) PAINT_WIDGET_LAYERS is not set and aRenderingContext is non-null;
+   * we paint by construct a BasicLayerManager and calling
+   * BeginTransactionWithTarget on it. This is desirable if we're doing
+   * something like drawWindow in a mode where what gets rendered doesn't
+   * necessarily correspond to what's visible in the window; we don't
+   * want to mess up the widget's layer tree.
+   */
+  static void PaintFrame(gfxContext* aRenderingContext, nsIFrame* aFrame,
+                         const nsRegion& aDirtyRegion, nscolor aBackstop,
+                         nsDisplayListBuilderMode aBuilderMode,
+                         PaintFrameFlags aFlags = PaintFrameFlags(0));
+
+  /**
+   * Uses a binary search for find where the cursor falls in the line of text
+   * It also keeps track of the part of the string that has already been
+   * measured so it doesn't have to keep measuring the same text over and over.
+   *
+   * @param "aBaseWidth" contains the width in twips of the portion
+   * of the text that has already been measured, and aBaseInx contains
+   * the index of the text that has already been measured.
+   *
+   * @param aTextWidth returns (in twips) the length of the text that falls
+   * before the cursor aIndex contains the index of the text where the cursor
+   * falls.
+   */
+  static bool BinarySearchForPosition(DrawTarget* aDrawTarget,
+                                      nsFontMetrics& aFontMetrics,
+                                      const char16_t* aText, int32_t aBaseWidth,
+                                      int32_t aBaseInx, int32_t aStartInx,
+                                      int32_t aEndInx, int32_t aCursorPos,
+                                      int32_t& aIndex, int32_t& aTextWidth);
+
+  class BoxCallback {
+   public:
+    BoxCallback() = default;
+    virtual void AddBox(nsIFrame* aFrame) = 0;
+    bool mIncludeCaptionBoxForTable = true;
+    // Whether we are in a continuation or ib-split-sibling of the target we're
+    // measuring. This is useful because if we know we're in the target subtree
+    // and measuring against it we can avoid finding the common ancestor.
+    bool mInTargetContinuation = false;
+  };
+  /**
+   * Collect all CSS boxes associated with aFrame and its
+   * continuations, "drilling down" through table wrapper frames and
+   * some anonymous blocks since they're not real CSS boxes.
+   * If aFrame is null, no boxes are returned.
+   * SVG frames return a single box, themselves.
+   */
+  static void GetAllInFlowBoxes(nsIFrame* aFrame, BoxCallback* aCallback);
+
+  /**
+   * Like GetAllInFlowBoxes, but doesn't include continuations.
+   */
+  static void AddBoxesForFrame(nsIFrame* aFrame, BoxCallback* aCallback);
+
+  /**
+   * Find the first frame descendant of aFrame (including aFrame) which is
+   * not an anonymous frame that getBoxQuads/getClientRects should ignore.
+   */
+  static nsIFrame* GetFirstNonAnonymousFrame(nsIFrame* aFrame);
+
+  struct RectAccumulator : public mozilla::RectCallback {
+    nsRect mResultRect;
+    nsRect mFirstRect;
+    bool mSeenFirstRect;
+
+    RectAccumulator();
+
+    virtual void AddRect(const nsRect& aRect) override;
+  };
+
+  struct RectListBuilder : public mozilla::RectCallback {
+    DOMRectList* mRectList;
+
+    explicit RectListBuilder(DOMRectList* aList);
+    virtual void AddRect(const nsRect& aRect) override;
+  };
+
+  static nsIFrame* GetContainingBlockForClientRect(nsIFrame* aFrame);
+
+  enum {
+    RECTS_ACCOUNT_FOR_TRANSFORMS = 0x01,
+    // Two bits for specifying which box type to use.
+    // With neither bit set (default), use the border box.
+    RECTS_USE_CONTENT_BOX = 0x02,
+    RECTS_USE_PADDING_BOX = 0x04,
+    RECTS_USE_MARGIN_BOX = 0x06,  // both bits set
+    RECTS_WHICH_BOX_MASK = 0x06   // bitmask for these two bits
+  };
+  /**
+   * Collect all CSS boxes (content, padding, border, or margin) associated
+   * with aFrame and its continuations, "drilling down" through table wrapper
+   * frames and some anonymous blocks since they're not real CSS boxes.
+   * The boxes are positioned relative to aRelativeTo (taking scrolling
+   * into account) and passed to the callback in frame-tree order.
+   * If aFrame is null, no boxes are returned.
+   * For SVG frames, returns one rectangle, the bounding box.
+   * If aFlags includes RECTS_ACCOUNT_FOR_TRANSFORMS, then when converting
+   * the boxes into aRelativeTo coordinates, transforms (including CSS
+   * and SVG transforms) are taken into account.
+   * If aFlags includes one of RECTS_USE_CONTENT_BOX, RECTS_USE_PADDING_BOX,
+   * or RECTS_USE_MARGIN_BOX, the corresponding type of box is used.
+   * Otherwise (by default), the border box is used.
+   */
+  static void GetAllInFlowRects(nsIFrame* aFrame, const nsIFrame* aRelativeTo,
+                                mozilla::RectCallback* aCallback,
+                                uint32_t aFlags = 0);
+
+  static void GetAllInFlowRectsAndTexts(
+      nsIFrame* aFrame, const nsIFrame* aRelativeTo,
+      mozilla::RectCallback* aCallback,
+      mozilla::dom::Sequence<nsString>* aTextList, uint32_t aFlags = 0);
+
+  /**
+   * Computes the union of all rects returned by GetAllInFlowRects. If
+   * the union is empty, returns the first rect.
+   * If aFlags includes RECTS_ACCOUNT_FOR_TRANSFORMS, then when converting
+   * the boxes into aRelativeTo coordinates, transforms (including CSS
+   * and SVG transforms) are taken into account.
+   * If aFlags includes one of RECTS_USE_CONTENT_BOX, RECTS_USE_PADDING_BOX,
+   * or RECTS_USE_MARGIN_BOX, the corresponding type of box is used.
+   * Otherwise (by default), the border box is used.
+   */
+  static nsRect GetAllInFlowRectsUnion(nsIFrame* aFrame,
+                                       const nsIFrame* aRelativeTo,
+                                       uint32_t aFlags = 0);
+
+  enum { EXCLUDE_BLUR_SHADOWS = 0x01 };
+  /**
+   * Takes a text-shadow array from the style properties of a given nsIFrame and
+   * computes the union of those shadows along with the given initial rect.
+   * If there are no shadows, the initial rect is returned.
+   */
+  static nsRect GetTextShadowRectsUnion(const nsRect& aTextAndDecorationsRect,
+                                        nsIFrame* aFrame, uint32_t aFlags = 0);
+
+  /**
+   * Computes the destination rect that a given replaced element should render
+   * into, based on its CSS 'object-fit' and 'object-position' properties.
+   *
+   * @param aConstraintRect The constraint rect that we have at our disposal,
+   *                        which would e.g. be exactly filled by the image
+   *                        if we had "object-fit: fill".
+   * @param aIntrinsicSize The replaced content's intrinsic size, as reported
+   *                       by nsIFrame::GetIntrinsicSize().
+   * @param aIntrinsicRatio The replaced content's intrinsic ratio, as reported
+   *                        by nsIFrame::GetIntrinsicRatio().
+   * @param aStylePos The nsStylePosition struct that contains the 'object-fit'
+   *                  and 'object-position' values that we should rely on.
+   *                  (This should usually be the nsStylePosition for the
+   *                  replaced element in question, but not always. For
+   *                  example, a <video>'s poster-image has a dedicated
+   *                  anonymous element & child-frame, but we should still use
+   *                  the <video>'s 'object-fit' and 'object-position' values.)
+   * @param aAnchorPoint [out] A point that should be pixel-aligned by functions
+   *                           like nsLayoutUtils::DrawImage. See documentation
+   *                           in nsCSSRendering.h for ComputeObjectAnchorPoint.
+   * @return The nsRect into which we should render the replaced content (using
+   *         the same coordinate space as the passed-in aConstraintRect).
+   */
+  static nsRect ComputeObjectDestRect(const nsRect& aConstraintRect,
+                                      const IntrinsicSize& aIntrinsicSize,
+                                      const AspectRatio& aIntrinsicRatio,
+                                      const nsStylePosition* aStylePos,
+                                      nsPoint* aAnchorPoint = nullptr);
+
+  /**
+   * Get the font metrics corresponding to the frame's style data.
+   * @param aFrame the frame
+   * @param aSizeInflation number to multiply font size by
+   */
+  static already_AddRefed<nsFontMetrics> GetFontMetricsForFrame(
+      const nsIFrame* aFrame, float aSizeInflation);
+
+  static already_AddRefed<nsFontMetrics> GetInflatedFontMetricsForFrame(
+      const nsIFrame* aFrame) {
+    return GetFontMetricsForFrame(aFrame, FontSizeInflationFor(aFrame));
+  }
+
+  /**
+   * Get the font metrics corresponding to the given style data.
+   * @param aComputedStyle the style data
+   * @param aSizeInflation number to multiply font size by
+   */
+  static already_AddRefed<nsFontMetrics> GetFontMetricsForComputedStyle(
+      const ComputedStyle* aComputedStyle, nsPresContext* aPresContext,
+      float aSizeInflation = 1.0f,
+      uint8_t aVariantWidth = NS_FONT_VARIANT_WIDTH_NORMAL);
+
+  /**
+   * Get the font metrics of emphasis marks corresponding to the given
+   * style data. The result is same as GetFontMetricsForComputedStyle
+   * except that the font size is scaled down to 50%.
+   * @param aComputedStyle the style data
+   * @param aInflation number to multiple font size by
+   */
+  static already_AddRefed<nsFontMetrics> GetFontMetricsOfEmphasisMarks(
+      ComputedStyle* aComputedStyle, nsPresContext* aPresContext,
+      float aInflation) {
+    return GetFontMetricsForComputedStyle(aComputedStyle, aPresContext,
+                                          aInflation * 0.5f);
+  }
+
+  /**
+   * Find the immediate child of aParent whose frame subtree contains
+   * aDescendantFrame. Returns null if aDescendantFrame is not a descendant
+   * of aParent.
+   */
+  static nsIFrame* FindChildContainingDescendant(nsIFrame* aParent,
+                                                 nsIFrame* aDescendantFrame);
+
+  /**
+   * Find the nearest ancestor that's a block
+   */
+  static nsBlockFrame* FindNearestBlockAncestor(nsIFrame* aFrame);
+
+  /**
+   * Find the nearest ancestor that's not for generated content. Will return
+   * aFrame if aFrame is not for generated content.
+   */
+  static nsIFrame* GetNonGeneratedAncestor(nsIFrame* aFrame);
+
+  /*
+   * Whether the frame is an nsBlockFrame which is not a wrapper block.
+   */
+  static bool IsNonWrapperBlock(nsIFrame* aFrame);
+
+  /**
+   * If aFrame is an out of flow frame, return its placeholder, otherwise
+   * return its parent.
+   */
+  static nsIFrame* GetParentOrPlaceholderFor(const nsIFrame* aFrame);
+
+  /**
+   * If aFrame is an out of flow frame, return its placeholder, otherwise
+   * return its (possibly cross-doc) parent.
+   */
+  static nsIFrame* GetParentOrPlaceholderForCrossDoc(const nsIFrame* aFrame);
+
+  /**
+   * Returns the frame that would act as the parent of aFrame when
+   * descending through the frame tree in display list building.
+   * Usually the same as GetParentOrPlaceholderForCrossDoc, except
+   * that pushed floats are treated as children of their containing
+   * block.
+   */
+  static nsIFrame* GetDisplayListParent(nsIFrame* aFrame);
+
+  /**
+   * Get a frame's previous continuation, or, if it doesn't have one, its
+   * previous block-in-inline-split sibling.
+   */
+  static nsIFrame* GetPrevContinuationOrIBSplitSibling(const nsIFrame* aFrame);
+
+  /**
+   * Get a frame's next continuation, or, if it doesn't have one, its
+   * block-in-inline-split sibling.
+   */
+  static nsIFrame* GetNextContinuationOrIBSplitSibling(const nsIFrame* aFrame);
+
+  /**
+   * Get the first frame in the continuation-plus-ib-split-sibling chain
+   * containing aFrame.
+   */
+  static nsIFrame* FirstContinuationOrIBSplitSibling(const nsIFrame* aFrame);
+
+  /**
+   * Get the last frame in the continuation-plus-ib-split-sibling chain
+   * containing aFrame.
+   */
+  static nsIFrame* LastContinuationOrIBSplitSibling(const nsIFrame* aFrame);
+
+  /**
+   * Is FirstContinuationOrIBSplitSibling(aFrame) going to return
+   * aFrame?
+   */
+  static bool IsFirstContinuationOrIBSplitSibling(const nsIFrame* aFrame);
+
+  /**
+   * Check whether aFrame is a part of the scrollbar or scrollcorner of
+   * the root content.
+   * @param aFrame the checking frame.
+   * @return true if the frame is a part of the scrollbar or scrollcorner of
+   *         the root content.
+   */
+  static bool IsViewportScrollbarFrame(nsIFrame* aFrame);
+
+  /**
+   * Get the contribution of aFrame to its containing block's intrinsic
+   * size for the given physical axis.  This considers the child's intrinsic
+   * width, its 'width', 'min-width', and 'max-width' properties (or 'height'
+   * variations if that's what matches aAxis) and its padding, border and margin
+   * in the corresponding dimension.
+   * @param aPercentageBasis an optional percentage basis (in aFrame's WM).
+   *   If the basis is indefinite in a given axis, pass a size with
+   *   NS_UNCONSTRAINEDSIZE in that component.
+   *   If you pass Nothing() a percentage basis will be calculated from aFrame's
+   *   ancestors' computed size in the relevant axis, if needed.
+   * @param aMarginBoxMinSizeClamp make the result fit within this margin-box
+   * size by reducing the *content size* (flooring at zero).  This is used for:
+   * https://drafts.csswg.org/css-grid/#min-size-auto
+   */
+  enum {
+    IGNORE_PADDING = 0x01,
+    BAIL_IF_REFLOW_NEEDED = 0x02,  // returns NS_INTRINSIC_ISIZE_UNKNOWN if so
+    MIN_INTRINSIC_ISIZE = 0x04,  // use min-width/height instead of width/height
+  };
+  static nscoord IntrinsicForAxis(
+      mozilla::PhysicalAxis aAxis, gfxContext* aRenderingContext,
+      nsIFrame* aFrame, mozilla::IntrinsicISizeType aType,
+      const mozilla::Maybe<LogicalSize>& aPercentageBasis = mozilla::Nothing(),
+      uint32_t aFlags = 0, nscoord aMarginBoxMinSizeClamp = NS_MAXSIZE);
+  /**
+   * Calls IntrinsicForAxis with aFrame's parent's inline physical axis.
+   */
+  static nscoord IntrinsicForContainer(gfxContext* aRenderingContext,
+                                       nsIFrame* aFrame,
+                                       mozilla::IntrinsicISizeType aType,
+                                       uint32_t aFlags = 0);
+
+  /**
+   * Get the definite size contribution of aFrame for the given physical axis.
+   * This considers the child's 'min-width' property (or 'min-height' if the
+   * given axis is vertical), and its padding, border, and margin in the
+   * corresponding dimension.  If the 'min-' property is 'auto' (and 'overflow'
+   * is 'visible') and the corresponding 'width'/'height' is definite it returns
+   * the "specified size" for:
+   * https://drafts.csswg.org/css-grid/#min-size-auto
+   * Note that the "transferred size" is not handled here; use IntrinsicForAxis.
+   * Note that any percentage in 'width'/'height' makes it count as indefinite.
+   * If the 'min-' property is 'auto' and 'overflow' is not 'visible', then it
+   * calculates the result as if the 'min-' computed value is zero.
+   * Otherwise, return NS_UNCONSTRAINEDSIZE.
+   *
+   * @param aPercentageBasis the percentage basis (in aFrame's WM).
+   *   Pass NS_UNCONSTRAINEDSIZE if the basis is indefinite in either/both axes.
+   * @note this behavior is specific to Grid/Flexbox (currently) so aFrame
+   * should be a grid/flex item.
+   */
+  static nscoord MinSizeContributionForAxis(mozilla::PhysicalAxis aAxis,
+                                            gfxContext* aRC, nsIFrame* aFrame,
+                                            mozilla::IntrinsicISizeType aType,
+                                            const LogicalSize& aPercentageBasis,
+                                            uint32_t aFlags = 0);
+
+  /*
+   * Convert LengthPercentage to nscoord when percentages depend on the
+   * containing block size.
+   * @param aPercentBasis The width or height of the containing block
+   * (whichever the client wants to use for resolving percentages).
+   */
+  static nscoord ComputeCBDependentValue(nscoord aPercentBasis,
+                                         const LengthPercentage& aCoord) {
+    NS_WARNING_ASSERTION(
+        aPercentBasis != NS_UNCONSTRAINEDSIZE,
+        "have unconstrained width or height; this should only result from very "
+        "large sizes, not attempts at intrinsic size calculation");
+    return aCoord.Resolve(aPercentBasis);
+  }
+  static nscoord ComputeCBDependentValue(nscoord aPercentBasis,
+                                         const LengthPercentageOrAuto& aCoord) {
+    if (aCoord.IsAuto()) {
+      return 0;
+    }
+    return ComputeCBDependentValue(aPercentBasis, aCoord.AsLengthPercentage());
+  }
+
+  static nscoord ComputeBSizeDependentValue(nscoord aContainingBlockBSize,
+                                            const LengthPercentageOrAuto&);
+
+  static nscoord ComputeBSizeValue(nscoord aContainingBlockBSize,
+                                   nscoord aContentEdgeToBoxSizingBoxEdge,
+                                   const LengthPercentage& aCoord) {
+    MOZ_ASSERT(aContainingBlockBSize != nscoord_MAX || !aCoord.HasPercent(),
+               "caller must deal with %% of unconstrained block-size");
+
+    nscoord result = aCoord.Resolve(aContainingBlockBSize);
+    // Clamp calc(), and the subtraction for box-sizing.
+    return std::max(0, result - aContentEdgeToBoxSizingBoxEdge);
+  }
+
+  /**
+   * The "extremum length" values (see ExtremumLength) were originally aimed at
+   * inline-size (or width, as it was before logicalization). For now, we return
+   * true for those here, so that we don't call ComputeBSizeValue with value
+   * types that it doesn't understand. (See bug 1113216.)
+   *
+   * FIXME (bug 567039, bug 527285)
+   * This isn't correct for the 'fill' value or for the 'min-*' or 'max-*'
+   * properties, which need to be handled differently by the callers of
+   * IsAutoBSize().
+   */
+  template <typename SizeOrMaxSize>
+  static bool IsAutoBSize(const SizeOrMaxSize& aCoord, nscoord aCBBSize) {
+    return aCoord.BehavesLikeInitialValueOnBlockAxis() ||
+           (aCBBSize == nscoord_MAX && aCoord.HasPercent());
+  }
+
+  static bool IsPaddingZero(const LengthPercentage& aLength) {
+    // clamp negative calc() to 0
+    return aLength.Resolve(nscoord_MAX) <= 0 && aLength.Resolve(0) <= 0;
+  }
+
+  static bool IsMarginZero(const LengthPercentage& aLength) {
+    return aLength.Resolve(nscoord_MAX) == 0 && aLength.Resolve(0) == 0;
+  }
+
+  static void MarkDescendantsDirty(nsIFrame* aSubtreeRoot);
+
+  static void MarkIntrinsicISizesDirtyIfDependentOnBSize(nsIFrame* aFrame);
+
+  /*
+   * Calculate the used values for 'width' and 'height' when width
+   * and height are 'auto'. The tentWidth and tentHeight arguments should be
+   * the result of applying the rules for computing intrinsic sizes and ratios.
+   * as specified by CSS 2.1 sections 10.3.2 and 10.6.2
+   */
+  static nsSize ComputeAutoSizeWithIntrinsicDimensions(
+      nscoord minWidth, nscoord minHeight, nscoord maxWidth, nscoord maxHeight,
+      nscoord tentWidth, nscoord tentHeight);
+
+  // Implement nsIFrame::GetPrefISize in terms of nsIFrame::AddInlinePrefISize
+  static nscoord PrefISizeFromInline(nsIFrame* aFrame,
+                                     gfxContext* aRenderingContext);
+
+  // Implement nsIFrame::GetMinISize in terms of nsIFrame::AddInlineMinISize
+  static nscoord MinISizeFromInline(nsIFrame* aFrame,
+                                    gfxContext* aRenderingContext);
+
+  // Get a suitable foreground color for painting aColor for aFrame.
+  static nscolor DarkenColorIfNeeded(nsIFrame* aFrame, nscolor aColor);
+
+  // Get a suitable foreground color for painting aField for aFrame.
+  // Type of aFrame is made a template parameter because nsIFrame is not
+  // a complete type in the header. Type-safety is not harmed given that
+  // DarkenColorIfNeeded requires an nsIFrame pointer.
+  template <typename Frame, typename T, typename S>
+  static nscolor GetColor(Frame* aFrame, T S::*aField) {
+    nscolor color = aFrame->GetVisitedDependentColor(aField);
+    return DarkenColorIfNeeded(aFrame, color);
+  }
+
+  // Get a baseline y position in app units that is snapped to device pixels.
+  static gfxFloat GetSnappedBaselineY(nsIFrame* aFrame, gfxContext* aContext,
+                                      nscoord aY, nscoord aAscent);
+  // Ditto for an x position (for vertical text). Note that for vertical-rl
+  // writing mode, the ascent value should be negated by the caller.
+  static gfxFloat GetSnappedBaselineX(nsIFrame* aFrame, gfxContext* aContext,
+                                      nscoord aX, nscoord aAscent);
+
+  static nscoord AppUnitWidthOfString(char16_t aC, nsFontMetrics& aFontMetrics,
+                                      DrawTarget* aDrawTarget) {
+    return AppUnitWidthOfString(&aC, 1, aFontMetrics, aDrawTarget);
+  }
+  static nscoord AppUnitWidthOfString(mozilla::Span<const char16_t> aString,
+                                      nsFontMetrics& aFontMetrics,
+                                      DrawTarget* aDrawTarget) {
+    return nsLayoutUtils::AppUnitWidthOfString(
+        aString.Elements(), aString.Length(), aFontMetrics, aDrawTarget);
+  }
+  static nscoord AppUnitWidthOfString(const char16_t* aString, uint32_t aLength,
+                                      nsFontMetrics& aFontMetrics,
+                                      DrawTarget* aDrawTarget);
+  static nscoord AppUnitWidthOfStringBidi(const nsString& aString,
+                                          const nsIFrame* aFrame,
+                                          nsFontMetrics& aFontMetrics,
+                                          gfxContext& aContext) {
+    return nsLayoutUtils::AppUnitWidthOfStringBidi(
+        aString.get(), aString.Length(), aFrame, aFontMetrics, aContext);
+  }
+  static nscoord AppUnitWidthOfStringBidi(const char16_t* aString,
+                                          uint32_t aLength,
+                                          const nsIFrame* aFrame,
+                                          nsFontMetrics& aFontMetrics,
+                                          gfxContext& aContext);
+
+  static bool StringWidthIsGreaterThan(const nsString& aString,
+                                       nsFontMetrics& aFontMetrics,
+                                       DrawTarget* aDrawTarget, nscoord aWidth);
+
+  static nsBoundingMetrics AppUnitBoundsOfString(const char16_t* aString,
+                                                 uint32_t aLength,
+                                                 nsFontMetrics& aFontMetrics,
+                                                 DrawTarget* aDrawTarget);
+
+  static void DrawString(const nsIFrame* aFrame, nsFontMetrics& aFontMetrics,
+                         gfxContext* aContext, const char16_t* aString,
+                         int32_t aLength, nsPoint aPoint,
+                         ComputedStyle* aComputedStyle = nullptr,
+                         DrawStringFlags aFlags = DrawStringFlags::Default);
+
+  static nsPoint GetBackgroundFirstTilePos(const nsPoint& aDest,
+                                           const nsPoint& aFill,
+                                           const nsSize& aRepeatSize);
+
+  /**
+   * Supports only LTR or RTL. Bidi (mixed direction) is not supported.
+   */
+  static void DrawUniDirString(const char16_t* aString, uint32_t aLength,
+                               const nsPoint& aPoint,
+                               nsFontMetrics& aFontMetrics,
+                               gfxContext& aContext);
+
+  /**
+   * Helper function for drawing text-shadow. The callback's job
+   * is to draw whatever needs to be blurred onto the given context.
+   */
+  typedef void (*TextShadowCallback)(gfxContext* aCtx, nsPoint aShadowOffset,
+                                     const nscolor& aShadowColor, void* aData);
+
+  static void PaintTextShadow(const nsIFrame* aFrame, gfxContext* aContext,
+                              const nsRect& aTextRect, const nsRect& aDirtyRect,
+                              const nscolor& aForegroundColor,
+                              TextShadowCallback aCallback,
+                              void* aCallbackData);
+
+  /**
+   * Gets the baseline to vertically center text from a font within a
+   * line of specified height.
+   * aIsInverted: true if the text is inverted relative to the block
+   * direction, so that the block-dir "ascent" corresponds to font
+   * descent. (Applies to sideways text in vertical-lr mode.)
+   *
+   * Returns the baseline position relative to the top of the line.
+   */
+  static nscoord GetCenteredFontBaseline(nsFontMetrics* aFontMetrics,
+                                         nscoord aLineHeight, bool aIsInverted);
+
+  /**
+   * Derive a baseline of |aFrame| (measured from its top border edge)
+   * from its first in-flow line box (not descending into anything with
+   * 'overflow' not 'visible', potentially including aFrame itself).
+   *
+   * Returns true if a baseline was found (and fills in aResult).
+   * Otherwise returns false.
+   */
+  static bool GetFirstLineBaseline(mozilla::WritingMode aWritingMode,
+                                   const nsIFrame* aFrame, nscoord* aResult);
+
+  /**
+   * Just like GetFirstLineBaseline, except also returns the top and
+   * bottom of the line with the baseline.
+   *
+   * Returns true if a line was found (and fills in aResult).
+   * Otherwise returns false.
+   */
+  struct LinePosition {
+    nscoord mBStart, mBaseline, mBEnd;
+
+    LinePosition operator+(nscoord aOffset) const {
+      LinePosition result;
+      result.mBStart = mBStart + aOffset;
+      result.mBaseline = mBaseline + aOffset;
+      result.mBEnd = mBEnd + aOffset;
+      return result;
+    }
+  };
+  static bool GetFirstLinePosition(mozilla::WritingMode aWritingMode,
+                                   const nsIFrame* aFrame,
+                                   LinePosition* aResult);
+
+  /**
+   * Derive a baseline of |aFrame| (measured from its top border edge)
+   * from its last in-flow line box (not descending into anything with
+   * 'overflow' not 'visible', potentially including aFrame itself).
+   *
+   * Returns true if a baseline was found (and fills in aResult).
+   * Otherwise returns false.
+   */
+  static bool GetLastLineBaseline(mozilla::WritingMode aWritingMode,
+                                  const nsIFrame* aFrame, nscoord* aResult);
+
+  /**
+   * Returns a block-dir coordinate relative to this frame's origin that
+   * represents the logical block-end of the frame or its visible content,
+   * whichever is further from the origin.
+   * Relative positioning is ignored and margins and glyph bounds are not
+   * considered.
+   * This value will be >= mRect.BSize() and <= overflowRect.BEnd() unless
+   * relative positioning is applied.
+   */
+  static nscoord CalculateContentBEnd(mozilla::WritingMode aWritingMode,
+                                      nsIFrame* aFrame);
+
+  /**
+   * Gets the closest frame (the frame passed in or one of its parents) that
+   * qualifies as a "layer"; used in DOM0 methods that depends upon that
+   * definition. This is the nearest frame that is either positioned or scrolled
+   * (the child of a scroll frame).
+   */
+  static nsIFrame* GetClosestLayer(nsIFrame* aFrame);
+
+  /**
+   * Gets the graphics sampling filter for the frame
+   */
+  static SamplingFilter GetSamplingFilterForFrame(nsIFrame* aFrame);
+
+  static inline void InitDashPattern(StrokeOptions& aStrokeOptions,
+                                     mozilla::StyleBorderStyle aBorderStyle) {
+    if (aBorderStyle == mozilla::StyleBorderStyle::Dotted) {
+      static Float dot[] = {1.f, 1.f};
+      aStrokeOptions.mDashLength = MOZ_ARRAY_LENGTH(dot);
+      aStrokeOptions.mDashPattern = dot;
+    } else if (aBorderStyle == mozilla::StyleBorderStyle::Dashed) {
+      static Float dash[] = {5.f, 5.f};
+      aStrokeOptions.mDashLength = MOZ_ARRAY_LENGTH(dash);
+      aStrokeOptions.mDashPattern = dash;
+    } else {
+      aStrokeOptions.mDashLength = 0;
+      aStrokeOptions.mDashPattern = nullptr;
+    }
+  }
+
+  /**
+   * Convert an nsRect to a gfxRect.
+   */
+  static gfxRect RectToGfxRect(const nsRect& aRect,
+                               int32_t aAppUnitsPerDevPixel);
+
+  static gfxPoint PointToGfxPoint(const nsPoint& aPoint,
+                                  int32_t aAppUnitsPerPixel) {
+    return gfxPoint(gfxFloat(aPoint.x) / aAppUnitsPerPixel,
+                    gfxFloat(aPoint.y) / aAppUnitsPerPixel);
+  }
+
+  /* N.B. The only difference between variants of the Draw*Image
+   * functions below is the type of the aImage argument.
+   */
+
+  /**
+   * Draw a background image.  The image's dimensions are as specified in aDest;
+   * the image itself is not consulted to determine a size.
+   * See https://wiki.mozilla.org/Gecko:Image_Snapping_and_Rendering
+   *
+   * @param aContext
+   *   The context to draw to, already set up with an appropriate scale and
+   *   transform for drawing in app units.
+   * @param aForFrame
+   *   The nsIFrame that we're drawing this image for.
+   * @param aImage
+   *   The image.
+   * @param aDest
+   *  The position and scaled area where one copy of the image should be drawn.
+   *  This area represents the image itself in its correct position as defined
+   *  with the background-position css property.
+   * @param aFill
+   *  The area to be filled with copies of the image.
+   * @param aRepeatSize
+   *  The distance between the positions of two subsequent repeats of the image.
+   *  Sizes larger than aDest.Size() create gaps between the images.
+   * @param aAnchor
+   *  A point in aFill which we will ensure is pixel-aligned in the output.
+   * @param aDirty
+   *   Pixels outside this area may be skipped.
+   * @param aImageFlags
+   *   Image flags of the imgIContainer::FLAG_* variety.
+   * @param aExtendMode
+   *   How to extend the image over the dest rect.
+   */
+  static ImgDrawResult DrawBackgroundImage(
+      gfxContext& aContext, nsIFrame* aForFrame, nsPresContext* aPresContext,
+      imgIContainer* aImage, SamplingFilter aSamplingFilter,
+      const nsRect& aDest, const nsRect& aFill, const nsSize& aRepeatSize,
+      const nsPoint& aAnchor, const nsRect& aDirty, uint32_t aImageFlags,
+      ExtendMode aExtendMode, float aOpacity);
+
+  /**
+   * Draw an image.
+   * See https://wiki.mozilla.org/Gecko:Image_Snapping_and_Rendering
+   *   @param aRenderingContext Where to draw the image, set up with an
+   *                            appropriate scale and transform for drawing in
+   *                            app units.
+   *   @param aComputedStyle    The ComputedStyle of the nsIFrame (or
+   *                            pseudo-element) for which this image is being
+   *                            drawn.
+   *   @param aImage            The image.
+   *   @param aDest             Where one copy of the image should mapped to.
+   *   @param aFill             The area to be filled with copies of the
+   *                            image.
+   *   @param aAnchor           A point in aFill which we will ensure is
+   *                            pixel-aligned in the output.
+   *   @param aDirty            Pixels outside this area may be skipped.
+   *   @param aImageFlags       Image flags of the imgIContainer::FLAG_* variety
+   */
+  static ImgDrawResult DrawImage(gfxContext& aContext,
+                                 ComputedStyle* aComputedStyle,
+                                 nsPresContext* aPresContext,
+                                 imgIContainer* aImage,
+                                 const SamplingFilter aSamplingFilter,
+                                 const nsRect& aDest, const nsRect& aFill,
+                                 const nsPoint& aAnchor, const nsRect& aDirty,
+                                 uint32_t aImageFlags, float aOpacity = 1.0);
+
+  /**
+   * Draw a whole image without scaling or tiling.
+   *
+   *   @param aRenderingContext Where to draw the image, set up with an
+   *                            appropriate scale and transform for drawing in
+   *                            app units.
+   *   @param aImage            The image.
+   *   @param aDest             The top-left where the image should be drawn.
+   *   @param aDirty            If non-null, then pixels outside this area may
+   *                            be skipped.
+   *   @param aSVGContext       Optionally provides an SVGImageContext.
+   *                            Callers should pass an SVGImageContext with at
+   *                            least the viewport size set if aImage may be of
+   *                            type imgIContainer::TYPE_VECTOR, or pass
+   *                            Nothing() if it is of type
+   *                            imgIContainer::TYPE_RASTER (to save cycles
+   *                            constructing an SVGImageContext, since this
+   *                            argument will be ignored for raster images).
+   *   @param aImageFlags       Image flags of the imgIContainer::FLAG_* variety
+   *   @param aSourceArea       If non-null, this area is extracted from
+   *                            the image and drawn at aDest. It's
+   *                            in appunits. For best results it should
+   *                            be aligned with image pixels.
+   */
+  static ImgDrawResult DrawSingleUnscaledImage(
+      gfxContext& aContext, nsPresContext* aPresContext, imgIContainer* aImage,
+      const SamplingFilter aSamplingFilter, const nsPoint& aDest,
+      const nsRect* aDirty, const mozilla::SVGImageContext& aSVGContext,
+      uint32_t aImageFlags, const nsRect* aSourceArea = nullptr);
+
+  /**
+   * Draw a whole image without tiling.
+   *
+   *   @param aRenderingContext Where to draw the image, set up with an
+   *                            appropriate scale and transform for drawing in
+   *                            app units.
+   *   @param aImage            The image.
+   *   @param aDest             The area that the image should fill.
+   *   @param aDirty            Pixels outside this area may be skipped.
+   *   @param aSVGContext       Optionally provides an SVGImageContext.
+   *                            Callers should pass an SVGImageContext with at
+   *                            least the viewport size set if aImage may be of
+   *                            type imgIContainer::TYPE_VECTOR, or pass
+   *                            Nothing() if it is of type
+   *                            imgIContainer::TYPE_RASTER (to save cycles
+   *                            constructing an SVGImageContext, since this
+   *                            argument will be ignored for raster images).
+   *   @param aImageFlags       Image flags of the imgIContainer::FLAG_*
+   *                            variety.
+   *   @param aAnchor           If non-null, a point which we will ensure
+   *                            is pixel-aligned in the output.
+   *   @param aSourceArea       If non-null, this area is extracted from
+   *                            the image and drawn in aDest. It's
+   *                            in appunits. For best results it should
+   *                            be aligned with image pixels.
+   */
+  static ImgDrawResult DrawSingleImage(
+      gfxContext& aContext, nsPresContext* aPresContext, imgIContainer* aImage,
+      SamplingFilter aSamplingFilter, const nsRect& aDest, const nsRect& aDirty,
+      const mozilla::SVGImageContext& aSVGContext, uint32_t aImageFlags,
+      const nsPoint* aAnchorPoint = nullptr,
+      const nsRect* aSourceArea = nullptr);
+
+  /**
+   * Given an imgIContainer, this method attempts to obtain an intrinsic
+   * px-valued height & width for it.  If the imgIContainer has a non-pixel
+   * value for either height or width, this method tries to generate a pixel
+   * value for that dimension using the intrinsic ratio (if available).  The
+   * intrinsic ratio will be assigned to aIntrinsicRatio; if there's no
+   * intrinsic ratio then (0, 0) will be assigned.
+   *
+   * This method will always set aGotWidth and aGotHeight to indicate whether
+   * we were able to successfully obtain (or compute) a value for each
+   * dimension.
+   *
+   * NOTE: This method is similar to ComputeSizeWithIntrinsicDimensions.  The
+   * difference is that this one is simpler and is suited to places where we
+   * have less information about the frame tree.
+   *
+   * @param aResolution The resolution specified by the author for the image, or
+   *                    its intrinsic resolution.
+   *
+   *                    This will affect the intrinsic size size of the image
+   *                    (so e.g., if resolution is 2, and the image is 100x100,
+   *                    the intrinsic size of the image will be 50x50).
+   */
+  static void ComputeSizeForDrawing(imgIContainer* aImage,
+                                    const mozilla::image::Resolution&,
+                                    CSSIntSize& aImageSize,
+                                    AspectRatio& aIntrinsicRatio,
+                                    bool& aGotWidth, bool& aGotHeight);
+
+  /**
+   * Given an imgIContainer, this method attempts to obtain an intrinsic
+   * px-valued height & width for it. If the imgIContainer has a non-pixel
+   * value for either height or width, this method tries to generate a pixel
+   * value for that dimension using the intrinsic ratio (if available). If,
+   * after trying all these methods, no value is available for one or both
+   * dimensions, the corresponding dimension of aFallbackSize is used instead.
+   */
+  static CSSIntSize ComputeSizeForDrawingWithFallback(
+      imgIContainer* aImage, const mozilla::image::Resolution&,
+      const nsSize& aFallbackSize);
+
+  /**
+   * Given the image container, frame, and dest rect, determine the best fitting
+   * size to decode the image at, and calculate any necessary SVG parameters.
+   */
+  static mozilla::gfx::IntSize ComputeImageContainerDrawingParameters(
+      imgIContainer* aImage, nsIFrame* aForFrame,
+      const LayoutDeviceRect& aDestRect, const LayoutDeviceRect& aFillRect,
+      const StackingContextHelper& aSc, uint32_t aFlags,
+      mozilla::SVGImageContext& aSVGContext,
+      mozilla::Maybe<mozilla::image::ImageIntRegion>& aRegion);
+
+  /**
+   * Given a source area of an image (in appunits) and a destination area
+   * that we want to map that source area too, computes the area that
+   * would be covered by the whole image. This is useful for passing to
+   * the aDest parameter of DrawImage, when we want to draw a subimage
+   * of an overall image.
+   */
+  static nsRect GetWholeImageDestination(const nsSize& aWholeImageSize,
+                                         const nsRect& aImageSourceArea,
+                                         const nsRect& aDestArea);
+
+  /**
+   * Given an image container and an orientation, returns an image container
+   * that contains the same image, reoriented appropriately. May return the
+   * original image container if no changes are needed.
+   *
+   * @param aContainer   The image container to apply the orientation to.
+   * @param aOrientation The desired orientation.
+   */
+  static already_AddRefed<imgIContainer> OrientImage(
+      imgIContainer* aContainer,
+      const mozilla::StyleImageOrientation& aOrientation);
+
+  /**
+   * Determine if any corner radius is of nonzero size
+   *   @param aCorners the |BorderRadius| object to check
+   *   @return true unless all the coordinates are 0%, 0 or null.
+   *
+   * A corner radius with one dimension zero and one nonzero is
+   * treated as a nonzero-radius corner, even though it will end up
+   * being rendered like a zero-radius corner.  This is because such
+   * corners are not expected to appear outside of test cases, and it's
+   * simpler to implement the test this way.
+   */
+  static bool HasNonZeroCorner(const mozilla::BorderRadius& aCorners);
+
+  /**
+   * Determine if there is any corner radius on corners adjacent to the
+   * given side.
+   */
+  static bool HasNonZeroCornerOnSide(const mozilla::BorderRadius& aCorners,
+                                     mozilla::Side aSide);
+
+  /**
+   * Determine if a widget is likely to require transparency or translucency.
+   *   @param aBackgroundFrame The frame that the background is set on. For
+   *                           <window>s, this will be the canvas frame.
+   *   @param aCSSRootFrame    The frame that holds CSS properties affecting
+   *                           the widget's transparency. For menupopups,
+   *                           aBackgroundFrame and aCSSRootFrame will be the
+   *                           same.
+   *   @return a value suitable for passing to SetWindowTranslucency.
+   */
+  static nsTransparencyMode GetFrameTransparency(nsIFrame* aBackgroundFrame,
+                                                 nsIFrame* aCSSRootFrame);
+
+  /**
+   * A frame is a popup if it has its own floating window. Menus, panels
+   * and combobox dropdowns are popups.
+   */
+  static bool IsPopup(const nsIFrame* aFrame);
+
+  /**
+   * Find the nearest "display root". This is the nearest enclosing
+   * popup frame or the root prescontext's root frame.
+   */
+  static nsIFrame* GetDisplayRootFrame(nsIFrame* aFrame);
+  static const nsIFrame* GetDisplayRootFrame(const nsIFrame* aFrame);
+
+  /**
+   * Get the reference frame that would be used when constructing a
+   * display item for this frame.  Rather than using their own frame
+   * as a reference frame.)
+   *
+   * This duplicates some of the logic of GetDisplayRootFrame above and
+   * of nsDisplayListBuilder::FindReferenceFrameFor.
+   *
+   * If you have an nsDisplayListBuilder, you should get the reference
+   * frame from it instead of calling this.
+   */
+  static nsIFrame* GetReferenceFrame(nsIFrame* aFrame);
+
+  /**
+   * Get textrun construction flags determined by a given style; in particular
+   * some combination of:
+   * -- TEXT_DISABLE_OPTIONAL_LIGATURES if letter-spacing is in use
+   * -- TEXT_OPTIMIZE_SPEED if the text-rendering CSS property and font size
+   * and prefs indicate we should be optimizing for speed over quality
+   */
+  static mozilla::gfx::ShapedTextFlags GetTextRunFlagsForStyle(
+      const ComputedStyle*, nsPresContext*, const nsStyleFont*,
+      const nsStyleText*, nscoord aLetterSpacing);
+
+  /**
+   * Get orientation flags for textrun construction.
+   */
+  static mozilla::gfx::ShapedTextFlags GetTextRunOrientFlagsForStyle(
+      const ComputedStyle*);
+
+  /**
+   * Takes two rectangles whose origins must be the same, and computes
+   * the difference between their union and their intersection as two
+   * rectangles. (This difference is a superset of the difference
+   * between the two rectangles.)
+   */
+  static void GetRectDifferenceStrips(const nsRect& aR1, const nsRect& aR2,
+                                      nsRect* aHStrip, nsRect* aVStrip);
+
+  /**
+   * Get a device context that can be used to get up-to-date device
+   * dimensions for the given window. For some reason, this is more
+   * complicated than it ought to be in multi-monitor situations.
+   */
+  static nsDeviceContext* GetDeviceContextForScreenInfo(
+      nsPIDOMWindowOuter* aWindow);
+
+  /**
+   * Some frames with 'position: fixed' (nsStyleDisplay::mPosition ==
+   * StylePositionProperty::Fixed) are not really fixed positioned, since
+   * they're inside an element with -moz-transform.  This function says
+   * whether such an element is a real fixed-pos element.
+   */
+  static bool IsReallyFixedPos(const nsIFrame* aFrame);
+
+  /**
+   * This function says whether `aFrame` would really be a fixed positioned
+   * frame if the frame was created with StylePositionProperty::Fixed.
+   *
+   * It is effectively the same as IsReallyFixedPos, but without asserting the
+   * position value. Use it only when you know what you're doing, like when
+   * tearing down the frame tree (where styles may have changed due to
+   * ::first-line reparenting and rule changes at the same time).
+   */
+  static bool MayBeReallyFixedPos(const nsIFrame* aFrame);
+
+  /**
+   * Returns true if |aFrame| is inside position:fixed subtree.
+   */
+  static bool IsInPositionFixedSubtree(const nsIFrame* aFrame);
+
+  /**
+   * Obtain a SourceSurface from the given DOM element, if possible.
+   * This obtains the most natural surface from the element; that
+   * is, the one that can be obtained with the fewest conversions.
+   *
+   * The flags below can modify the behaviour of this function.  The
+   * result is returned as a SurfaceFromElementResult struct, also
+   * defined below.
+   *
+   * Currently, this will do:
+   *  - HTML Canvas elements: will return the underlying canvas surface
+   *  - HTML Video elements: will return the current video frame
+   *  - Image elements: will return the image
+   *
+   * The above results are modified by the below flags (copying,
+   * forcing image surface, etc.).
+   */
+
+  enum {
+    /* Whether to extract the first frame (as opposed to the
+       current frame) in the case that the element is an image. */
+    SFE_WANT_FIRST_FRAME_IF_IMAGE = 1 << 0,
+    /* Whether we should skip colorspace/gamma conversion */
+    SFE_NO_COLORSPACE_CONVERSION = 1 << 1,
+    /* Caller handles SFER::mAlphaType = NonPremult */
+    SFE_ALLOW_NON_PREMULT = 1 << 2,
+    /* Whether we should skip getting a surface for vector images and
+       return a DirectDrawInfo containing an imgIContainer instead. */
+    SFE_NO_RASTERIZING_VECTORS = 1 << 3,
+    /* If image type is vector, the return surface size will same as
+       element size, not image's intrinsic size. */
+    SFE_USE_ELEMENT_SIZE_IF_VECTOR = 1 << 4,
+    /* Ensure that the returned surface has a size that matches the
+     * SurfaceFromElementResult::mSize. This is mostly a convenience thing so
+     * that callers who want this don't have to deal with it themselves.
+     * The surface might be different for, e.g., a EXIF-scaled raster image, if
+     * we don't rescale during decode. */
+    SFE_EXACT_SIZE_SURFACE = 1 << 6,
+  };
+
+  // This function can be called on any thread.
+  static mozilla::SurfaceFromElementResult SurfaceFromOffscreenCanvas(
+      mozilla::dom::OffscreenCanvas* aOffscreenCanvas, uint32_t aSurfaceFlags,
+      RefPtr<DrawTarget>& aTarget);
+  static mozilla::SurfaceFromElementResult SurfaceFromOffscreenCanvas(
+      mozilla::dom::OffscreenCanvas* aOffscreenCanvas,
+      uint32_t aSurfaceFlags = 0) {
+    RefPtr<DrawTarget> target = nullptr;
+    return SurfaceFromOffscreenCanvas(aOffscreenCanvas, aSurfaceFlags, target);
+  }
+  static mozilla::SurfaceFromElementResult SurfaceFromImageBitmap(
+      mozilla::dom::ImageBitmap* aImageBitmap, uint32_t aSurfaceFlags);
+
+  static mozilla::SurfaceFromElementResult SurfaceFromElement(
+      mozilla::dom::Element* aElement,
+      const mozilla::Maybe<int32_t>& aResizeWidth,
+      const mozilla::Maybe<int32_t>& aResizeHeight, uint32_t aSurfaceFlags,
+      RefPtr<DrawTarget>& aTarget);
+  static mozilla::SurfaceFromElementResult SurfaceFromElement(
+      mozilla::dom::Element* aElement, uint32_t aSurfaceFlags = 0) {
+    RefPtr<DrawTarget> target = nullptr;
+    return SurfaceFromElement(aElement, mozilla::Nothing(), mozilla::Nothing(),
+                              aSurfaceFlags, target);
+  }
+  static mozilla::SurfaceFromElementResult SurfaceFromElement(
+      mozilla::dom::Element* aElement, uint32_t aSurfaceFlags,
+      RefPtr<DrawTarget>& aTarget) {
+    return SurfaceFromElement(aElement, mozilla::Nothing(), mozilla::Nothing(),
+                              aSurfaceFlags, aTarget);
+  }
+  static mozilla::SurfaceFromElementResult SurfaceFromElement(
+      mozilla::dom::Element* aElement,
+      const mozilla::Maybe<int32_t>& aResizeWidth,
+      const mozilla::Maybe<int32_t>& aResizeHeight,
+      uint32_t aSurfaceFlags = 0) {
+    RefPtr<DrawTarget> target = nullptr;
+    return SurfaceFromElement(aElement, aResizeWidth, aResizeHeight,
+                              aSurfaceFlags, target);
+  }
+
+  // There are a bunch of callers of SurfaceFromElement.  Just mark it as
+  MOZ_CAN_RUN_SCRIPT_BOUNDARY
+  static mozilla::SurfaceFromElementResult SurfaceFromElement(
+      nsIImageLoadingContent* aElement,
+      const mozilla::Maybe<int32_t>& aResizeWidth,
+      const mozilla::Maybe<int32_t>& aResizeHeight, uint32_t aSurfaceFlags,
+      RefPtr<DrawTarget>& aTarget);
+  // Need an HTMLImageElement overload, because otherwise the
+  // nsIImageLoadingContent and mozilla::dom::Element overloads are ambiguous
+  // for HTMLImageElement.
+  static mozilla::SurfaceFromElementResult SurfaceFromElement(
+      mozilla::dom::HTMLImageElement* aElement, uint32_t aSurfaceFlags,
+      RefPtr<DrawTarget>& aTarget);
+  static mozilla::SurfaceFromElementResult SurfaceFromElement(
+      mozilla::dom::HTMLCanvasElement* aElement, uint32_t aSurfaceFlags,
+      RefPtr<DrawTarget>& aTarget);
+  static mozilla::SurfaceFromElementResult SurfaceFromElement(
+      mozilla::dom::HTMLCanvasElement* aElement, uint32_t aSurfaceFlags) {
+    RefPtr<DrawTarget> target = nullptr;
+    return SurfaceFromElement(aElement, aSurfaceFlags, target);
+  }
+  static mozilla::SurfaceFromElementResult SurfaceFromElement(
+      mozilla::dom::HTMLVideoElement* aElement, uint32_t aSurfaceFlags,
+      RefPtr<DrawTarget>& aTarget);
+
+  /**
+   * When the document is editable by contenteditable attribute of its root
+   * content or body content.
+   *
+   * Be aware, this returns nullptr if it's in designMode.
+   *
+   * For example:
+   *
+   *  <html contenteditable="true"><body></body></html>
+   *    returns the <html>.
+   *
+   *  <html><body contenteditable="true"></body></html>
+   *  <body contenteditable="true"></body>
+   *    With these cases, this returns the <body>.
+   *    NOTE: The latter case isn't created normally, however, it can be
+   *          created by script with XHTML.
+   *
+   *  <body><p contenteditable="true"></p></body>
+   *    returns nullptr because <body> isn't editable.
+   */
+  static mozilla::dom::Element* GetEditableRootContentByContentEditable(
+      mozilla::dom::Document* aDocument);
+
+  static void AddExtraBackgroundItems(nsDisplayListBuilder* aBuilder,
+                                      nsDisplayList* aList, nsIFrame* aFrame,
+                                      const nsRect& aCanvasArea,
+                                      const nsRegion& aVisibleRegion,
+                                      nscolor aBackstop);
+
+  /**
+   * Returns true if the passed in prescontext needs the dark grey background
+   * that goes behind the page of a print preview presentation.
+   */
+  static bool NeedsPrintPreviewBackground(nsPresContext* aPresContext);
+
+  /**
+   * Types used by the helpers for InspectorUtils.getUsedFontFaces.
+   * The API returns an array (UsedFontFaceList) that owns the
+   * InspectorFontFace instances, but during range traversal we also
+   * want to maintain a mapping from gfxFontEntry to InspectorFontFace
+   * records, so use a temporary hashtable for that.
+   */
+  typedef nsTArray<mozilla::UniquePtr<mozilla::dom::InspectorFontFace>>
+      UsedFontFaceList;
+  typedef nsTHashMap<nsPtrHashKey<gfxFontEntry>,
+                     mozilla::dom::InspectorFontFace*>
+      UsedFontFaceTable;
+
+  /**
+   * Adds all font faces used in the frame tree starting from aFrame
+   * to the list aFontFaceList.
+   * aMaxRanges: maximum number of text ranges to record for each face.
+   */
+  static nsresult GetFontFacesForFrames(nsIFrame* aFrame,
+                                        UsedFontFaceList& aResult,
+                                        UsedFontFaceTable& aFontFaces,
+                                        uint32_t aMaxRanges,
+                                        bool aSkipCollapsedWhitespace);
+
+  /**
+   * Adds all font faces used within the specified range of text in aFrame,
+   * and optionally its continuations, to the list in aFontFaceList.
+   * Pass 0 and INT32_MAX for aStartOffset and aEndOffset to specify the
+   * entire text is to be considered.
+   * aMaxRanges: maximum number of text ranges to record for each face.
+   */
+  static void GetFontFacesForText(nsIFrame* aFrame, int32_t aStartOffset,
+                                  int32_t aEndOffset, bool aFollowContinuations,
+                                  UsedFontFaceList& aResult,
+                                  UsedFontFaceTable& aFontFaces,
+                                  uint32_t aMaxRanges,
+                                  bool aSkipCollapsedWhitespace);
+
+  /**
+   * Walks the frame tree starting at aFrame looking for textRuns.
+   * If |clear| is true, just clears the TEXT_RUN_MEMORY_ACCOUNTED flag
+   * on each textRun found (and |aMallocSizeOf| is not used).
+   * If |clear| is false, adds the storage used for each textRun to the
+   * total, and sets the TEXT_RUN_MEMORY_ACCOUNTED flag to avoid double-
+   * accounting. (Runs with this flag already set will be skipped.)
+   * Expected usage pattern is therefore to call twice:
+   *    (void)SizeOfTextRunsForFrames(rootFrame, nullptr, true);
+   *    total = SizeOfTextRunsForFrames(rootFrame, mallocSizeOf, false);
+   */
+  static size_t SizeOfTextRunsForFrames(nsIFrame* aFrame,
+                                        mozilla::MallocSizeOf aMallocSizeOf,
+                                        bool clear);
+
+  /**
+   * Returns true if |aFrame| has an animation of a property in |aPropertySet|
+   * regardless of whether any property in the set is overridden by an
+   * !important rule.
+   */
+  static bool HasAnimationOfPropertySet(const nsIFrame* aFrame,
+                                        const nsCSSPropertyIDSet& aPropertySet);
+
+  /**
+   * A variant of the above HasAnimationOfPropertySet that takes an optional
+   * EffectSet parameter as an optimization to save redundant lookups of the
+   * EffectSet.
+   */
+  static bool HasAnimationOfPropertySet(const nsIFrame* aFrame,
+                                        const nsCSSPropertyIDSet& aPropertySet,
+                                        mozilla::EffectSet* aEffectSet);
+
+  /**
+   * A variant of the above HasAnimationOfPropertySet. This is especially for
+   * tranform-like properties with motion-path.
+   * For transform-like properties with motion-path, we need to check if
+   * offset-path has effect. If we don't have any animation on offset-path and
+   * offset-path is none, there is no effective motion-path, and so we don't
+   * care other offset-* properties. In this case, this function only checks the
+   * rest of transform-like properties (i.e. transform/translate/rotate/scale).
+   */
+  static bool HasAnimationOfTransformAndMotionPath(const nsIFrame* aFrame);
+
+  /**
+   * Returns true if |aFrame| has an animation of |aProperty| which is
+   * not overridden by !important rules.
+   */
+  static bool HasEffectiveAnimation(const nsIFrame* aFrame,
+                                    nsCSSPropertyID aProperty);
+
+  /**
+   * Returns true if |aFrame| has an animation where at least one of the
+   * properties in |aPropertySet| is not overridden by !important rules.
+   *
+   * If |aPropertySet| includes transform-like properties (transform, rotate,
+   * etc.) however, this will return false if any of the transform-like
+   * properties is overriden by an !important rule since these properties should
+   * be combined on the compositor.
+   */
+  static bool HasEffectiveAnimation(const nsIFrame* aFrame,
+                                    const nsCSSPropertyIDSet& aPropertySet);
+
+  /**
+   * Returns all effective animated CSS properties on |aStyleFrame| and its
+   * corresponding primary frame (for content that makes this distinction,
+   * notable display:table content) that can be animated on the compositor.
+   *
+   * Properties that can be animated on the compositor but which are overridden
+   * by !important rules are not returned.
+   *
+   * Unlike HasEffectiveAnimation, however, this does not check the set of
+   * transform-like properties to ensure that if any such properties are
+   * overridden by !important rules, the other transform-like properties are
+   * not run on the compositor (see bug 1534884).
+   */
+  static nsCSSPropertyIDSet GetAnimationPropertiesForCompositor(
+      const nsIFrame* aStyleFrame);
+
+  /**
+   * Checks if off-main-thread animations are enabled.
+   */
+  static bool AreAsyncAnimationsEnabled();
+
+  /**
+   * Checks if retained display lists are enabled.
+   */
+  static bool AreRetainedDisplayListsEnabled();
+
+  static bool DisplayRootHasRetainedDisplayListBuilder(nsIFrame* aFrame);
+
+  static RetainedDisplayListBuilder* GetRetainedDisplayListBuilder(
+      nsIFrame* aFrame);
+
+  /**
+   * Find a suitable scale for a element (aFrame's content) over the course of
+   * any animations and transitions of the CSS transform property on the element
+   * that run on the compositor thread. It will check the maximum and minimum
+   * scale during the animations and transitions and return a suitable value for
+   * performance and quality. Will return scale(1,1) if there are no such
+   * animations. Always returns a positive value.
+   * @param aVisibleSize is the size of the area we want to paint
+   * @param aDisplaySize is the size of the display area of the pres context
+   */
+  static MatrixScales ComputeSuitableScaleForAnimation(
+      const nsIFrame* aFrame, const nsSize& aVisibleSize,
+      const nsSize& aDisplaySize);
+
+  /**
+   * Checks whether we want to use the GPU to scale images when
+   * possible.
+   */
+  static bool GPUImageScalingEnabled();
+
+  /**
+   * Unions the overflow areas of the children of aFrame with aOverflowAreas.
+   * aSkipChildLists specifies any child lists that should be skipped.
+   * FrameChildListID::Popup is always skipped.
+   */
+  static void UnionChildOverflow(
+      nsIFrame* aFrame, mozilla::OverflowAreas& aOverflowAreas,
+      mozilla::FrameChildListIDs aSkipChildLists = {});
+
+  /**
+   * Return the font size inflation *ratio* for a given frame.  This is
+   * the factor by which font sizes should be inflated; it is never
+   * smaller than 1.
+   */
+  static float FontSizeInflationFor(const nsIFrame* aFrame);
+
+  /**
+   * Perform the first half of the computation of FontSizeInflationFor
+   * (see above).
+   * This includes determining whether inflation should be performed
+   * within this container and returning 0 if it should not be.
+   *
+   * The result is guaranteed not to vary between line participants
+   * (inlines, text frames) within a line.
+   *
+   * The result should not be used directly since font sizes slightly
+   * above the minimum should always be adjusted as done by
+   * FontSizeInflationInner.
+   */
+  static nscoord InflationMinFontSizeFor(const nsIFrame* aFrame);
+
+  /**
+   * Perform the second half of the computation done by
+   * FontSizeInflationFor (see above).
+   *
+   * aMinFontSize must be the result of one of the
+   *   InflationMinFontSizeFor methods above.
+   */
+  static float FontSizeInflationInner(const nsIFrame* aFrame,
+                                      nscoord aMinFontSize);
+
+  static bool FontSizeInflationEnabled(nsPresContext* aPresContext);
+
+  /**
+   * Returns true if the nglayout.debug.invalidation pref is set to true.
+   */
+  static bool InvalidationDebuggingIsEnabled() {
+    return mozilla::StaticPrefs::nglayout_debug_invalidation() ||
+           getenv("MOZ_DUMP_INVALIDATION") != 0;
+  }
+
+  static void Initialize();
+  static void Shutdown();
+
+  /**
+   * Register an imgIRequest object with a refresh driver.
+   *
+   * @param aPresContext The nsPresContext whose refresh driver we want to
+   *        register with.
+   * @param aRequest A pointer to the imgIRequest object which the client wants
+   *        to register with the refresh driver.
+   * @param aRequestRegistered A pointer to a boolean value which indicates
+   *        whether the given image request is registered. If
+   *        *aRequestRegistered is true, then this request will not be
+   *        registered again. If the request is registered by this function,
+   *        then *aRequestRegistered will be set to true upon the completion of
+   *        this function.
+   *
+   */
+  static void RegisterImageRequest(nsPresContext* aPresContext,
+                                   imgIRequest* aRequest,
+                                   bool* aRequestRegistered);
+
+  /**
+   * Register an imgIRequest object with a refresh driver, but only if the
+   * request is for an image that is animated.
+   *
+   * @param aPresContext The nsPresContext whose refresh driver we want to
+   *        register with.
+   * @param aRequest A pointer to the imgIRequest object which the client wants
+   *        to register with the refresh driver.
+   * @param aRequestRegistered A pointer to a boolean value which indicates
+   *        whether the given image request is registered. If
+   *        *aRequestRegistered is true, then this request will not be
+   *        registered again. If the request is registered by this function,
+   *        then *aRequestRegistered will be set to true upon the completion of
+   *        this function.
+   *
+   */
+  static void RegisterImageRequestIfAnimated(nsPresContext* aPresContext,
+                                             imgIRequest* aRequest,
+                                             bool* aRequestRegistered);
+
+  /**
+   * Deregister an imgIRequest object from a refresh driver.
+   *
+   * @param aPresContext The nsPresContext whose refresh driver we want to
+   *        deregister from.
+   * @param aRequest A pointer to the imgIRequest object with which the client
+   *        previously registered and now wants to deregister from the refresh
+   *        driver.
+   * @param aRequestRegistered A pointer to a boolean value which indicates
+   *        whether the given image request is registered. If
+   *        *aRequestRegistered is false, then this request will not be
+   *        deregistered. If the request is deregistered by this function,
+   *        then *aRequestRegistered will be set to false upon the completion of
+   *        this function.
+   */
+  static void DeregisterImageRequest(nsPresContext* aPresContext,
+                                     imgIRequest* aRequest,
+                                     bool* aRequestRegistered);
+
+  /**
+   * Shim to nsCSSFrameConstructor::PostRestyleEvent. Exists so that we
+   * can avoid including nsCSSFrameConstructor.h and all its dependencies
+   * in content files.
+   */
+  static void PostRestyleEvent(mozilla::dom::Element*, mozilla::RestyleHint,
+                               nsChangeHint aMinChangeHint);
+
+  /**
+   * Updates a pair of x and y distances if a given point is closer to a given
+   * rectangle than the original distance values.  If aPoint is closer to
+   * aRect than aClosestXDistance and aClosestYDistance indicate, then those
+   * two variables are updated with the distance between aPoint and aRect,
+   * and true is returned.  If aPoint is not closer, then aClosestXDistance
+   * and aClosestYDistance are left unchanged, and false is returned.
+   *
+   * Distances are measured in the two dimensions separately; a closer x
+   * distance beats a closer y distance.
+   */
+  template <typename PointType, typename RectType, typename CoordType>
+  static bool PointIsCloserToRect(PointType aPoint, const RectType& aRect,
+                                  CoordType& aClosestXDistance,
+                                  CoordType& aClosestYDistance);
+  /**
+   * Computes the box shadow rect for the frame, or returns an empty rect if
+   * there are no shadows.
+   *
+   * @param aFrame Frame to compute shadows for.
+   * @param aFrameSize Size of aFrame (in case it hasn't been set yet).
+   */
+  static nsRect GetBoxShadowRectForFrame(nsIFrame* aFrame,
+                                         const nsSize& aFrameSize);
+
+#ifdef DEBUG
+  /**
+   * Assert that there are no duplicate continuations of the same frame
+   * within aFrameList.  Optimize the tests by assuming that all frames
+   * in aFrameList have parent aContainer.
+   */
+  static void AssertNoDuplicateContinuations(nsIFrame* aContainer,
+                                             const nsFrameList& aFrameList);
+
+  /**
+   * Assert that the frame tree rooted at |aSubtreeRoot| is empty, i.e.,
+   * that it contains no first-in-flows.
+   */
+  static void AssertTreeOnlyEmptyNextInFlows(nsIFrame* aSubtreeRoot);
+#endif
+
+  /**
+   * Helper method to transform |aBounds| from aFrame to aAncestorFrame,
+   * and combine it with |aPreciseTargetDest| if it is axis-aligned, or
+   * combine it with |aImpreciseTargetDest| if not. The transformed rect is
+   * clipped to |aClip|; if |aClip| has rounded corners, that also causes
+   * the imprecise target to be used.
+   */
+  static void TransformToAncestorAndCombineRegions(
+      const nsRegion& aRegion, nsIFrame* aFrame, const nsIFrame* aAncestorFrame,
+      nsRegion* aPreciseTargetDest, nsRegion* aImpreciseTargetDest,
+      mozilla::Maybe<Matrix4x4Flagged>* aMatrixCache,
+      const mozilla::DisplayItemClip* aClip);
+
+  /**
+   * Populate aOutSize with the size of the content viewer corresponding
+   * to the given prescontext. Return true if the size was set, false
+   * otherwise.
+   */
+  enum class SubtractDynamicToolbar { No, Yes };
+  static bool GetContentViewerSize(
+      const nsPresContext* aPresContext, LayoutDeviceIntSize& aOutSize,
+      SubtractDynamicToolbar = SubtractDynamicToolbar::Yes);
+
+ private:
+  static bool UpdateCompositionBoundsForRCDRSF(
+      mozilla::ParentLayerRect& aCompBounds, const nsPresContext* aPresContext);
+
+ public:
+  /**
+   * Calculate the compostion size for a frame. See FrameMetrics.h for
+   * defintion of composition size (or bounds).
+   * Note that for the root content document's root scroll frame (RCD-RSF),
+   * the returned size does not change as the document's resolution changes,
+   * but for all other frames it does. This means that callers that pass in
+   * a frame that may or may not be the RCD-RSF (which is most callers),
+   * are likely to need special-case handling of the RCD-RSF.
+   */
+  static nsSize CalculateCompositionSizeForFrame(
+      nsIFrame* aFrame, bool aSubtractScrollbars = true,
+      const nsSize* aOverrideScrollPortSize = nullptr);
+
+  /**
+   * Calculate a size suitable for bounding the size of the composition bounds
+   * of scroll frames in the current process. This should be at most the
+   * composition size of the cross-process RCD-RSF, but it may be a tighter
+   * bounding size.
+   * @param aFrame A frame in the (in-process) root content document (or a
+   *          descendant of it).
+   * @param aIsRootContentDocRootScrollFrame Whether aFrame is the root
+   *          scroll frame of the *cross-process* root content document.
+   *          In this case we just use aFrame's own composition size.
+   * @param aMetrics A partially populated FrameMetrics for aFrame. Must have at
+   *          least mCompositionBounds, mCumulativeResolution, and
+   *          mDevPixelsPerCSSPixel set.
+   */
+  static CSSSize CalculateBoundingCompositionSize(
+      const nsIFrame* aFrame, bool aIsRootContentDocRootScrollFrame,
+      const FrameMetrics& aMetrics);
+
+  /**
+   * Calculate the scrollable rect for a frame. See FrameMetrics.h for
+   * defintion of scrollable rect. aScrollableFrame is the scroll frame to
+   * calculate the scrollable rect for. If it's null then we calculate the
+   * scrollable rect as the rect of the root frame.
+   */
+  static nsRect CalculateScrollableRectForFrame(
+      const nsIScrollableFrame* aScrollableFrame, const nsIFrame* aRootFrame);
+
+  /**
+   * Calculate the expanded scrollable rect for a frame. See FrameMetrics.h for
+   * defintion of expanded scrollable rect.
+   */
+  static nsRect CalculateExpandedScrollableRect(nsIFrame* aFrame);
+
+  /**
+   * Returns true if the widget owning the given frame uses asynchronous
+   * scrolling.
+   */
+  static bool UsesAsyncScrolling(nsIFrame* aFrame);
+
+  /**
+   * Returns true if the widget owning the given frame has builtin APZ support
+   * enabled.
+   */
+  static bool AsyncPanZoomEnabled(const nsIFrame* aFrame);
+
+  /**
+   * Returns true if aDocument should be allowed to use resolution
+   * zooming.
+   */
+  static bool AllowZoomingForDocument(const mozilla::dom::Document* aDocument);
+
+  /**
+   * Returns true if we need to disable async scrolling for this particular
+   * element. Note that this does a partial disabling - the displayport still
+   * exists but uses a very small margin, and the compositor doesn't apply the
+   * async transform. However, the content may still be layerized.
+   */
+  static bool ShouldDisableApzForElement(nsIContent* aContent);
+
+  /**
+   * Log a key/value pair as "additional data" (not associated with a paint)
+   * for APZ testing.
+   * While the data is not associated with a paint, the APZTestData object
+   * is still owned by {Client,WebRender}LayerManager, so we need to be passed
+   * something from which we can derive the layer manager.
+   * This function takes a display list builder as the object to derive the
+   * layer manager from, to facilitate logging test data during display list
+   * building, but other overloads that take other objects could be added if
+   * desired.
+   */
+  static void LogAdditionalTestData(nsDisplayListBuilder* aBuilder,
+                                    const std::string& aKey,
+                                    const std::string& aValue);
+
+  /**
+   * Log a key/value pair for APZ testing during a paint.
+   * @param aManager   The data will be written to the APZTestData associated
+   *                   with this layer manager.
+   * @param aScrollId Identifies the scroll frame to which the data pertains.
+   * @param aKey The key under which to log the data.
+   * @param aValue The value of the data to be logged.
+   */
+  static void LogTestDataForPaint(
+      mozilla::layers::WebRenderLayerManager* aManager, ViewID aScrollId,
+      const std::string& aKey, const std::string& aValue) {
+    DoLogTestDataForPaint(aManager, aScrollId, aKey, aValue);
+  }
+
+  /**
+   * A convenience overload of LogTestDataForPaint() that accepts any type
+   * as the value, and passes it through mozilla::ToString() to obtain a string
+   * value. The type passed must support streaming to an std::ostream.
+   */
+  template <typename Value>
+  static void LogTestDataForPaint(
+      mozilla::layers::WebRenderLayerManager* aManager, ViewID aScrollId,
+      const std::string& aKey, const Value& aValue) {
+    DoLogTestDataForPaint(aManager, aScrollId, aKey, mozilla::ToString(aValue));
+  }
+
+  /**
+   * Calculate a basic FrameMetrics with enough fields set to perform some
+   * layout calculations. The fields set are dev-to-css ratio, pres shell
+   * resolution, cumulative resolution, zoom, composition size, root
+   * composition size, scroll offset and scrollable rect.
+   *
+   * Note that for the RCD-RSF, the scroll offset returned is the layout
+   * viewport offset; if you need the visual viewport offset, that needs to
+   * be queried independently via PresShell::GetVisualViewportOffset().
+   *
+   * By contrast, ComputeFrameMetrics() computes all the fields, but requires
+   * extra inputs and can only be called during frame layer building.
+   */
+  static FrameMetrics CalculateBasicFrameMetrics(
+      nsIScrollableFrame* aScrollFrame);
+
+  static nsIScrollableFrame* GetAsyncScrollableAncestorFrame(nsIFrame* aTarget);
+
+  static void SetBSizeFromFontMetrics(
+      const nsIFrame* aFrame, mozilla::ReflowOutput& aMetrics,
+      const mozilla::LogicalMargin& aFramePadding, mozilla::WritingMode aLineWM,
+      mozilla::WritingMode aFrameWM);
+
+  static bool HasDocumentLevelListenersForApzAwareEvents(PresShell* aPresShell);
+
+  /**
+   * Returns true if the given scroll origin is "higher priority" than APZ.
+   * In general any content programmatic scrolls (e.g. scrollTo calls) are
+   * higher priority, and take precedence over APZ scrolling. This function
+   * returns true for those, and returns false for other origins like APZ
+   * itself, or scroll position updates from the history restore code.
+   */
+  static bool CanScrollOriginClobberApz(ScrollOrigin aScrollOrigin);
+
+  static ScrollMetadata ComputeScrollMetadata(
+      const nsIFrame* aForFrame, const nsIFrame* aScrollFrame,
+      nsIContent* aContent, const nsIFrame* aItemFrame,
+      const nsPoint& aOffsetToReferenceFrame,
+      mozilla::layers::WebRenderLayerManager* aLayerManager,
+      ViewID aScrollParentId, const nsSize& aScrollPortSize, bool aIsRoot);
+
+  /**
+   * Returns the metadata to put onto the root layer of a layer tree, if one is
+   * needed. The last argument is a callback function to check if the caller
+   * already has a metadata for a given scroll id.
+   */
+  static mozilla::Maybe<ScrollMetadata> GetRootMetadata(
+      nsDisplayListBuilder* aBuilder,
+      mozilla::layers::WebRenderLayerManager* aLayerManager,
+      const std::function<bool(ViewID& aScrollId)>& aCallback);
+
+  /**
+   * If the given scroll frame needs an area excluded from its composition
+   * bounds due to scrollbars, return that area, otherwise return an empty
+   * margin.
+   * There is no need to exclude scrollbars in the following cases:
+   *   - If the scroll frame is not the RCD-RSF; in that case, the composition
+   *     bounds is calculated based on the scroll port which already excludes
+   *     the scrollbar area.
+   *   - If the scrollbars are overlay, since then they are drawn on top of the
+   *     scrollable content.
+   */
+  static nsMargin ScrollbarAreaToExcludeFromCompositionBoundsFor(
+      const nsIFrame* aScrollFrame);
+
+  static bool ShouldUseNoScriptSheet(mozilla::dom::Document*);
+  static bool ShouldUseNoFramesSheet(mozilla::dom::Document*);
+
+  /**
+   * Get the text content inside the frame. This methods traverse the
+   * frame tree and collect the content from text frames. Note that this
+   * method is similiar to nsContentUtils::GetNodeTextContent, but it at
+   * least differs from that method in the following things:
+   * 1. it skips text content inside nodes like style, script, textarea
+   *    which don't generate an in-tree text frame for the text;
+   * 2. it skips elements with display property set to none;
+   * 3. it skips out-of-flow elements;
+   * 4. it includes content inside pseudo elements;
+   * 5. it may include part of text content of a node if a text frame
+   *    inside is split to different continuations.
+   */
+  static void GetFrameTextContent(nsIFrame* aFrame, nsAString& aResult);
+
+  /**
+   * Same as GetFrameTextContent but appends the result rather than sets it.
+   */
+  static void AppendFrameTextContent(nsIFrame* aFrame, nsAString& aResult);
+
+  /**
+   * Takes a selection, and returns selection's bounding rect which is relative
+   * to its root frame.
+   *
+   * @param aSel      Selection to check
+   */
+  static nsRect GetSelectionBoundingRect(const mozilla::dom::Selection* aSel);
+
+  /**
+   * Calculate the bounding rect of |aContent|, relative to the origin
+   * of the scrolled content of |aRootScrollFrame|.
+   * Where the element is contained inside a scrollable subframe, the
+   * bounding rect is clipped to the bounds of the subframe.
+   * If non-null aOutNearestScrollClip will be filled in with the rect of the
+   * nearest scroll frame (excluding aRootScrollFrame) that is an ancestor of
+   * the frame of aContent, if such exists, in the same coords are the returned
+   * rect. This rect is used to clip the result.
+   */
+  static CSSRect GetBoundingContentRect(
+      const nsIContent* aContent, const nsIScrollableFrame* aRootScrollFrame,
+      mozilla::Maybe<CSSRect>* aOutNearestScrollClip = nullptr);
+
+  /**
+   * Similar to GetBoundingContentRect for nsIFrame.
+   */
+  static CSSRect GetBoundingFrameRect(
+      nsIFrame* aFrame, const nsIScrollableFrame* aRootScrollFrame,
+      mozilla::Maybe<CSSRect>* aOutNearestScrollClip = nullptr);
+
+  /**
+   * Returns the first ancestor who is a float containing block.
+   */
+  static nsBlockFrame* GetFloatContainingBlock(nsIFrame* aFrame);
+
+  /**
+   * Walks up the frame tree from |aForFrame| up to |aTopFrame|, or to the
+   * root of the frame tree if |aTopFrame| is nullptr, and returns true if
+   * a transformed frame is encountered.
+   */
+  static bool IsTransformed(nsIFrame* aForFrame, nsIFrame* aTopFrame = nullptr);
+
+  /**
+   * Walk up from aFrame to the cross-doc root, accumulating all the APZ
+   * callback transforms on the content elements encountered along the way.
+   * Return the accumulated value.
+   * XXX: Note that this does not take into account CSS transforms, nor
+   * differences in structure between the frame tree and the layer tree (which
+   * is probably what we *want* to be computing).
+   */
+  static CSSPoint GetCumulativeApzCallbackTransform(nsIFrame* aFrame);
+
+  /**
+   * Compute a rect to pre-render in cases where we want to render more of
+   * something than what is visible (usually to support async transformation).
+   * @param aFrame the target frame to be pre-rendered
+   * @param aDirtyRect the area that's visible in the coordinate system of
+   *        |aFrame|.
+   * @param aOverflow the total size of the thing we're rendering in the
+   *        coordinate system of |aFrame|.
+   * @param aPrerenderSize how large of an area we're willing to render in the
+   *        coordinate system of the root frame.
+   * @return A rectangle that includes |aDirtyRect|, is clamped to |aOverflow|,
+   *         and is no larger than |aPrerenderSize| (unless |aPrerenderSize| is
+   *         smaller than |aDirtyRect|, in which case the returned rect will
+   *         still include |aDirtyRect| and thus be larger than
+   *         |aPrerenderSize|).
+   */
+  static nsRect ComputePartialPrerenderArea(nsIFrame* aFrame,
+                                            const nsRect& aDirtyRect,
+                                            const nsRect& aOverflow,
+                                            const nsSize& aPrerenderSize);
+
+  /*
+   * Checks whether a node is an invisible break.
+   * If not, returns the first frame on the next line if such a next line
+   * exists.
+   *
+   * @return
+   *   true if the node is an invisible break. aNextLineFrame is returned null
+   *   in this case.
+   *
+   *   false if the node causes a visible break or if the node is no break.
+   *
+   * @param aNextLineFrame
+   *   assigned to first frame on the next line if such a next line exists, null
+   *   otherwise.
+   */
+  static bool IsInvisibleBreak(nsINode* aNode,
+                               nsIFrame** aNextLineFrame = nullptr);
+
+  static nsRect ComputeGeometryBox(nsIFrame*, StyleGeometryBox);
+
+  static nsRect ComputeGeometryBox(nsIFrame*,
+                                   const mozilla::StyleShapeGeometryBox&);
+
+  static nsRect ComputeGeometryBox(nsIFrame*, const mozilla::StyleShapeBox&);
+
+  static nsPoint ComputeOffsetToUserSpace(nsDisplayListBuilder* aBuilder,
+                                          nsIFrame* aFrame);
+
+  // Callers are responsible to ensure the user-font-set is up-to-date if
+  // aUseUserFontSet is true.
+  static already_AddRefed<nsFontMetrics> GetMetricsFor(
+      nsPresContext* aPresContext, bool aIsVertical,
+      const nsStyleFont* aStyleFont, mozilla::Length aFontSize,
+      bool aUseUserFontSet);
+
+  static void ComputeSystemFont(nsFont* aSystemFont,
+                                mozilla::StyleSystemFont aFontID,
+                                const nsFont& aDefaultVariableFont,
+                                const mozilla::dom::Document* aDocument);
+
+  static uint32_t ParseFontLanguageOverride(const nsAString& aLangTag);
+
+  /**
+   * Returns true if there are any preferences or overrides that indicate a
+   * need to handle <meta name="viewport"> tags.
+   */
+  static bool ShouldHandleMetaViewport(const mozilla::dom::Document*);
+
+  /**
+   * Resolve a CSS <length-percentage> value to a definite size.
+   */
+  template <bool clampNegativeResultToZero>
+  static nscoord ResolveToLength(const LengthPercentage& aLengthPercentage,
+                                 nscoord aPercentageBasis) {
+    nscoord value = (aPercentageBasis == NS_UNCONSTRAINEDSIZE)
+                        ? aLengthPercentage.Resolve(0)
+                        : aLengthPercentage.Resolve(aPercentageBasis);
+    return clampNegativeResultToZero ? std::max(0, value) : value;
+  }
+
+  /**
+   * Resolve a column-gap/row-gap to a definite size.
+   * @note This method resolves 'normal' to zero.
+   *   Callers who want different behavior should handle 'normal' on their own.
+   */
+  static nscoord ResolveGapToLength(
+      const mozilla::NonNegativeLengthPercentageOrNormal& aGap,
+      nscoord aPercentageBasis) {
+    if (aGap.IsNormal()) {
+      return nscoord(0);
+    }
+    return ResolveToLength<true>(aGap.AsLengthPercentage(), aPercentageBasis);
+  }
+
+  /**
+   * Get the computed style from which the scrollbar style should be
+   * used for the given scrollbar part frame.
+   */
+  static ComputedStyle* StyleForScrollbar(nsIFrame* aScrollbarPart);
+
+  /**
+   * Returns true if |aFrame| is scrolled out of view by a scrollable element in
+   * a cross-process ancestor document.
+   * Note this function only works for frames in out-of-process iframes.
+   **/
+  static bool FrameIsScrolledOutOfViewInCrossProcess(const nsIFrame* aFrame);
+
+  /**
+   * Similar to above FrameIsScrolledOutViewInCrossProcess but returns true even
+   * if |aFrame| is not fully scrolled out of view and its visible area width or
+   * height is smaller than |aMargin|.
+   **/
+  static bool FrameIsMostlyScrolledOutOfViewInCrossProcess(
+      const nsIFrame* aFrame, nscoord aMargin);
+
+  /**
+   * Expand the height of |aSize| to the size of `vh` units.
+   *
+   * With dynamic toolbar(s) the height for `vh` units is greater than the
+   * ICB height, we need to expand it in some places.
+   **/
+  static nsSize ExpandHeightForViewportUnits(nsPresContext* aPresContext,
+                                             const nsSize& aSize);
+
+  static CSSSize ExpandHeightForDynamicToolbar(
+      const nsPresContext* aPresContext, const CSSSize& aSize);
+  static nsSize ExpandHeightForDynamicToolbar(const nsPresContext* aPresContext,
+                                              const nsSize& aSize);
+
+  /**
+   * Returns the nsIFrame which clips overflow regions of the given |aFrame|.
+   * Note CSS clip or clip-path isn't accounted for.
+   **/
+  static nsIFrame* GetNearestOverflowClipFrame(nsIFrame* aFrame);
+
+ private:
+  /**
+   * Helper function for LogTestDataForPaint().
+   */
+  static void DoLogTestDataForPaint(
+      mozilla::layers::WebRenderLayerManager* aManager, ViewID aScrollId,
+      const std::string& aKey, const std::string& aValue);
+
+  static bool IsAPZTestLoggingEnabled();
+
+  static void ConstrainToCoordValues(gfxFloat& aStart, gfxFloat& aSize);
+  static void ConstrainToCoordValues(float& aStart, float& aSize);
+};
+
+MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(nsLayoutUtils::PaintFrameFlags)
+MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(nsLayoutUtils::GetPopupFrameForPointFlags)
+
+template <typename PointType, typename RectType, typename CoordType>
+/* static */ bool nsLayoutUtils::PointIsCloserToRect(
+    PointType aPoint, const RectType& aRect, CoordType& aClosestXDistance,
+    CoordType& aClosestYDistance) {
+  CoordType fromLeft = aPoint.x - aRect.x;
+  CoordType fromRight = aPoint.x - aRect.XMost();
+
+  CoordType xDistance;
+  if (fromLeft >= 0 && fromRight <= 0) {
+    xDistance = 0;
+  } else {
+    xDistance = std::min(abs(fromLeft), abs(fromRight));
+  }
+
+  if (xDistance <= aClosestXDistance) {
+    if (xDistance < aClosestXDistance) {
+      aClosestYDistance = std::numeric_limits<CoordType>::max();
+    }
+
+    CoordType fromTop = aPoint.y - aRect.y;
+    CoordType fromBottom = aPoint.y - aRect.YMost();
+
+    CoordType yDistance;
+    if (fromTop >= 0 && fromBottom <= 0) {
+      yDistance = 0;
+    } else {
+      yDistance = std::min(abs(fromTop), abs(fromBottom));
+    }
+
+    if (yDistance < aClosestYDistance) {
+      aClosestXDistance = xDistance;
+      aClosestYDistance = yDistance;
+      return true;
+    }
+  }
+
+  return false;
+}
+
+template <typename T>
+nsRect nsLayoutUtils::RoundGfxRectToAppRect(const T& aRect,
+                                            const float aFactor) {
+  // Get a new Rect whose units are app units by scaling by the specified
+  // factor.
+  T scaledRect = aRect;
+  scaledRect.ScaleRoundOut(aFactor);
+
+  // We now need to constrain our results to the max and min values for coords.
+  ConstrainToCoordValues(scaledRect.x, scaledRect.width);
+  ConstrainToCoordValues(scaledRect.y, scaledRect.height);
+
+  if (!aRect.Width()) {
+    scaledRect.SetWidth(0);
+  }
+
+  if (!aRect.Height()) {
+    scaledRect.SetHeight(0);
+  }
+
+  // Now typecast everything back.  This is guaranteed to be safe.
+  return nsRect(nscoord(scaledRect.X()), nscoord(scaledRect.Y()),
+                nscoord(scaledRect.Width()), nscoord(scaledRect.Height()));
+}
+
+namespace mozilla {
+
+/**
+ * Converts an nsPoint in app units to a Moz2D Point in pixels (whether those
+ * are device pixels or CSS px depends on what the caller chooses to pass as
+ * aAppUnitsPerPixel).
+ */
+inline gfx::Point NSPointToPoint(const nsPoint& aPoint,
+                                 int32_t aAppUnitsPerPixel) {
+  return gfx::Point(gfx::Float(aPoint.x) / aAppUnitsPerPixel,
+                    gfx::Float(aPoint.y) / aAppUnitsPerPixel);
+}
+
+/**
+ * Converts an nsRect in app units to a Moz2D Rect in pixels (whether those
+ * are device pixels or CSS px depends on what the caller chooses to pass as
+ * aAppUnitsPerPixel).
+ */
+gfx::Rect NSRectToRect(const nsRect& aRect, double aAppUnitsPerPixel);
+
+/**
+ * Converts an nsRect in app units to a Moz2D Rect in pixels (whether those
+ * are device pixels or CSS px depends on what the caller chooses to pass as
+ * aAppUnitsPerPixel).
+ *
+ * The passed DrawTarget is used to additionally snap the returned Rect to
+ * device pixels, if appropriate (as decided and carried out by Moz2D's
+ * MaybeSnapToDevicePixels helper, which this function calls to do any
+ * snapping).
+ */
+gfx::Rect NSRectToSnappedRect(const nsRect& aRect, double aAppUnitsPerPixel,
+                              const gfx::DrawTarget& aSnapDT);
+
+/**
+ * Converts, where possible, an nsRect in app units to a Moz2D Rect in pixels
+ * (whether those are device pixels or CSS px depends on what the caller
+ *  chooses to pass as aAppUnitsPerPixel).
+ *
+ * If snapping results in a rectangle with zero width or height, the affected
+ * coordinates are left unsnapped
+ */
+gfx::Rect NSRectToNonEmptySnappedRect(const nsRect& aRect,
+                                      double aAppUnitsPerPixel,
+                                      const gfx::DrawTarget& aSnapDT);
+
+void StrokeLineWithSnapping(
+    const nsPoint& aP1, const nsPoint& aP2, int32_t aAppUnitsPerDevPixel,
+    gfx::DrawTarget& aDrawTarget, const gfx::Pattern& aPattern,
+    const gfx::StrokeOptions& aStrokeOptions = gfx::StrokeOptions(),
+    const gfx::DrawOptions& aDrawOptions = gfx::DrawOptions());
+
+namespace layout {
+
+/**
+ * An RAII class which will, for the duration of its lifetime,
+ * **if** the frame given is a container for font size inflation,
+ * set the current inflation container on the pres context to null
+ * (and then, in its destructor, restore the old value).
+ */
+class AutoMaybeDisableFontInflation {
+ public:
+  explicit AutoMaybeDisableFontInflation(nsIFrame* aFrame);
+
+  ~AutoMaybeDisableFontInflation();
+
+ private:
+  nsPresContext* mPresContext;
+  bool mOldValue;
+};
+
+}  // namespace layout
+}  // namespace mozilla
+
+class nsSetAttrRunnable : public mozilla::Runnable {
+ public:
+  nsSetAttrRunnable(mozilla::dom::Element* aElement, nsAtom* aAttrName,
+                    const nsAString& aValue);
+  nsSetAttrRunnable(mozilla::dom::Element* aElement, nsAtom* aAttrName,
+                    int32_t aValue);
+
+  NS_DECL_NSIRUNNABLE
+
+  RefPtr<mozilla::dom::Element> mElement;
+  RefPtr<nsAtom> mAttrName;
+  nsAutoString mValue;
+};
+
+class nsUnsetAttrRunnable : public mozilla::Runnable {
+ public:
+  nsUnsetAttrRunnable(mozilla::dom::Element* aElement, nsAtom* aAttrName);
+
+  NS_DECL_NSIRUNNABLE
+
+  RefPtr<mozilla::dom::Element> mElement;
+  RefPtr<nsAtom> mAttrName;
+};
+
+// This class allows you to easily set any pointer variable and ensure it's
+// set to nullptr when leaving its scope.
+template <typename T>
+class MOZ_RAII SetAndNullOnExit {
+ public:
+  SetAndNullOnExit(T*& aVariable, T* aValue) {
+    aVariable = aValue;
+    mVariable = &aVariable;
+  }
+  ~SetAndNullOnExit() { *mVariable = nullptr; }
+
+ private:
+  T** mVariable;
+};
+
+#endif  // nsLayoutUtils_h__