Adding upstream version 86.0.1.upstream/86.0.1upstream

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

1 files changed, 1478 insertions, 0 deletions

diff --git a/layout/base/nsPresContext.h b/layout/base/nsPresContext.h
new file mode 100644
index 0000000000..375e1881fc
--- /dev/null
+++ b/layout/base/nsPresContext.h
@@ -0,0 +1,1478 @@
+/* -*- 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/. */
+
+/* a presentation of a document, part 1 */
+
+#ifndef nsPresContext_h___
+#define nsPresContext_h___
+
+#include "mozilla/AppUnits.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/EnumeratedArray.h"
+#include "mozilla/MediaEmulationData.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/NotNull.h"
+#include "mozilla/PreferenceSheet.h"
+#include "mozilla/PresShellForwards.h"
+#include "mozilla/ScrollStyles.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/WeakPtr.h"
+#include "mozilla/widget/ThemeChangeKind.h"
+#include "nsColor.h"
+#include "nsCompatibility.h"
+#include "nsCoord.h"
+#include "nsCOMPtr.h"
+#include "nsHashKeys.h"
+#include "nsRect.h"
+#include "nsStringFwd.h"
+#include "nsTHashtable.h"
+#include "nsAtom.h"
+#include "nsIWidgetListener.h"  // for nsSizeMode
+#include "nsGkAtoms.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsChangeHint.h"
+#include "gfxTypes.h"
+#include "gfxRect.h"
+#include "nsTArray.h"
+#include "nsThreadUtils.h"
+#include "Units.h"
+
+class nsBidi;
+class nsIPrintSettings;
+class nsDocShell;
+class nsIDocShell;
+class nsITheme;
+class nsITimer;
+class nsIContent;
+class nsIFrame;
+class nsFrameManager;
+class nsAtom;
+class nsIRunnable;
+class gfxFontFeatureValueSet;
+class gfxUserFontEntry;
+class gfxUserFontSet;
+class gfxTextPerfMetrics;
+class nsCSSFontFeatureValuesRule;
+class nsCSSFrameConstructor;
+class nsDisplayList;
+class nsDisplayListBuilder;
+class nsPluginFrame;
+class nsTransitionManager;
+class nsAnimationManager;
+class nsRefreshDriver;
+class nsIWidget;
+class nsDeviceContext;
+class gfxMissingFontRecorder;
+struct FontMatchingStats;
+
+namespace mozilla {
+class AnimationEventDispatcher;
+class EffectCompositor;
+class Encoding;
+class EventStateManager;
+class CounterStyleManager;
+class OneShotPostRefreshObserver;
+class PresShell;
+class RestyleManager;
+class ServoStyleSet;
+class StaticPresData;
+struct MediaFeatureChange;
+enum class MediaFeatureChangePropagation : uint8_t;
+namespace layers {
+class ContainerLayer;
+class LayerManager;
+}  // namespace layers
+namespace dom {
+class Document;
+class Element;
+}  // namespace dom
+}  // namespace mozilla
+
+// supported values for cached integer pref types
+enum nsPresContext_CachedIntPrefType {
+  kPresContext_ScrollbarSide = 1,
+  kPresContext_BidiDirection
+};
+
+// IDs for the default variable and fixed fonts (not to be changed, see
+// nsFont.h) To be used for Get/SetDefaultFont(). The other IDs in nsFont.h are
+// also supported.
+//
+// kGenericFont_moz_variable
+const uint8_t kPresContext_DefaultVariableFont_ID = 0x00;
+// kGenericFont_moz_fixed
+const uint8_t kPresContext_DefaultFixedFont_ID = 0x01;
+
+#ifdef DEBUG
+struct nsAutoLayoutPhase;
+
+enum class nsLayoutPhase : uint8_t {
+  Paint,
+  DisplayListBuilding,  // sometimes a subset of the paint phase
+  Reflow,
+  FrameC,
+  COUNT
+};
+#endif
+
+/* Used by nsPresContext::HasAuthorSpecifiedRules */
+#define NS_AUTHOR_SPECIFIED_BORDER_OR_BACKGROUND (1 << 0)
+#define NS_AUTHOR_SPECIFIED_PADDING (1 << 1)
+
+class nsRootPresContext;
+
+// An interface for presentation contexts. Presentation contexts are
+// objects that provide an outer context for a presentation shell.
+
+class nsPresContext : public nsISupports, public mozilla::SupportsWeakPtr {
+ public:
+  using Encoding = mozilla::Encoding;
+  template <typename T>
+  using NotNull = mozilla::NotNull<T>;
+  template <typename T>
+  using Maybe = mozilla::Maybe<T>;
+  using MediaEmulationData = mozilla::MediaEmulationData;
+  using StylePrefersColorScheme = mozilla::StylePrefersColorScheme;
+
+  typedef mozilla::ScrollStyles ScrollStyles;
+  using TransactionId = mozilla::layers::TransactionId;
+
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS_FINAL
+  NS_DECL_CYCLE_COLLECTION_CLASS(nsPresContext)
+
+  enum nsPresContextType : uint8_t {
+    eContext_Galley,        // unpaginated screen presentation
+    eContext_PrintPreview,  // paginated screen presentation
+    eContext_Print,         // paginated printer presentation
+    eContext_PageLayout     // paginated & editable.
+  };
+
+  nsPresContext(mozilla::dom::Document* aDocument, nsPresContextType aType);
+
+  /**
+   * Initialize the presentation context from a particular device.
+   */
+  nsresult Init(nsDeviceContext* aDeviceContext);
+
+  /**
+   * Set and detach presentation shell that this context is bound to.
+   * A presentation context may only be bound to a single shell.
+   */
+  void AttachPresShell(mozilla::PresShell* aPresShell);
+  void DetachPresShell();
+
+  nsPresContextType Type() const { return mType; }
+
+  /**
+   * Get the PresentationShell that this context is bound to.
+   */
+  mozilla::PresShell* PresShell() const {
+    NS_ASSERTION(mPresShell, "Null pres shell");
+    return mPresShell;
+  }
+
+  mozilla::PresShell* GetPresShell() const { return mPresShell; }
+
+  void DocumentCharSetChanged(NotNull<const Encoding*> aCharSet);
+
+  /**
+   * Returns the parent prescontext for this one. Returns null if this is a
+   * root.
+   */
+  nsPresContext* GetParentPresContext() const;
+
+  /**
+   * Returns the prescontext of the root content document in the same process
+   * that contains this presentation, or null if there isn't one.
+   */
+  nsPresContext* GetInProcessRootContentDocumentPresContext();
+
+  /**
+   * Returns the nearest widget for the root frame or view of this.
+   *
+   * @param aOffset     If non-null the offset from the origin of the root
+   *                    frame's view to the widget's origin (usually positive)
+   *                    expressed in appunits of this will be returned in
+   *                    aOffset.
+   */
+  nsIWidget* GetNearestWidget(nsPoint* aOffset = nullptr);
+
+  /**
+   * Returns the root widget for this.
+   */
+  nsIWidget* GetRootWidget() const;
+
+  /**
+   * Returns the widget which may have native focus and handles text input
+   * like keyboard input, IME, etc.
+   */
+  nsIWidget* GetTextInputHandlingWidget() const {
+    // Currently, root widget for each PresContext handles text input.
+    return GetRootWidget();
+  }
+
+  /**
+   * Return the presentation context for the root of the view manager
+   * hierarchy that contains this presentation context, or nullptr if it can't
+   * be found (e.g. it's detached).
+   */
+  nsRootPresContext* GetRootPresContext() const;
+
+  virtual bool IsRoot() { return false; }
+
+  mozilla::dom::Document* Document() const {
+#ifdef DEBUG
+    ValidatePresShellAndDocumentReleation();
+#endif  // #ifdef DEBUG
+    return mDocument;
+  }
+
+  inline mozilla::ServoStyleSet* StyleSet() const;
+
+  bool HasPendingMediaQueryUpdates() const {
+    return !!mPendingMediaFeatureValuesChange;
+  }
+
+  inline nsCSSFrameConstructor* FrameConstructor();
+
+  mozilla::AnimationEventDispatcher* AnimationEventDispatcher() {
+    return mAnimationEventDispatcher;
+  }
+
+  mozilla::EffectCompositor* EffectCompositor() { return mEffectCompositor; }
+  nsTransitionManager* TransitionManager() { return mTransitionManager.get(); }
+  nsAnimationManager* AnimationManager() { return mAnimationManager.get(); }
+  const nsAnimationManager* AnimationManager() const {
+    return mAnimationManager.get();
+  }
+
+  nsRefreshDriver* RefreshDriver() { return mRefreshDriver; }
+
+  mozilla::RestyleManager* RestyleManager() {
+    MOZ_ASSERT(mRestyleManager);
+    return mRestyleManager.get();
+  }
+
+  mozilla::CounterStyleManager* CounterStyleManager() const {
+    return mCounterStyleManager;
+  }
+
+  /**
+   * Rebuilds all style data by throwing out the old rule tree and
+   * building a new one, and additionally applying a change hint (which must not
+   * contain nsChangeHint_ReconstructFrame) to the root frame.
+   *
+   * For the restyle hint argument, see RestyleManager::RebuildAllStyleData.
+   * Also rebuild the user font set and counter style manager.
+   *
+   * FIXME(emilio): The name of this is an utter lie. We should probably call
+   * this PostGlobalStyleChange or something, as it doesn't really rebuild
+   * anything unless you tell it to via the change hint / restyle hint
+   * machinery.
+   */
+  void RebuildAllStyleData(nsChangeHint, const mozilla::RestyleHint&);
+  /**
+   * Just like RebuildAllStyleData, except (1) asynchronous and (2) it
+   * doesn't rebuild the user font set / counter-style manager / etc.
+   */
+  void PostRebuildAllStyleDataEvent(nsChangeHint, const mozilla::RestyleHint&);
+
+  void ContentLanguageChanged();
+
+  /** Returns whether any media query changed. */
+  bool FlushPendingMediaFeatureValuesChanged();
+
+  /**
+   * Schedule a media feature change for this document, and potentially for
+   * other subdocuments and images (depending on the arguments).
+   */
+  void MediaFeatureValuesChanged(const mozilla::MediaFeatureChange&,
+                                 mozilla::MediaFeatureChangePropagation);
+
+  /**
+   * Updates the size mode on all remote children and recursively notifies this
+   * document and all subdocuments (including remote children) that a media
+   * feature value has changed.
+   */
+  void SizeModeChanged(nsSizeMode aSizeMode);
+
+  /**
+   * Access compatibility mode for this context.  This is the same as
+   * our document's compatibility mode.
+   */
+  nsCompatibility CompatibilityMode() const;
+
+  /**
+   * Access the image animation mode for this context
+   */
+  uint16_t ImageAnimationMode() const { return mImageAnimationMode; }
+  void SetImageAnimationMode(uint16_t aMode);
+
+  /**
+   * Get medium of presentation
+   */
+  const nsAtom* Medium() {
+    MOZ_ASSERT(mMedium);
+    return mMediaEmulationData.mMedium ? mMediaEmulationData.mMedium.get()
+                                       : mMedium;
+  }
+
+  /*
+   * Render the document as if being viewed on a device with the specified
+   * media type.
+   *
+   * If passed null, it stops emulating.
+   */
+  void EmulateMedium(nsAtom* aMediaType);
+
+  /** Get a cached integer pref, by its type */
+  // *  - initially created for bugs 30910, 61883, 74186, 84398
+  int32_t GetCachedIntPref(nsPresContext_CachedIntPrefType aPrefType) const {
+    // If called with a constant parameter, the compiler should optimize
+    // this switch statement away.
+    switch (aPrefType) {
+      case kPresContext_ScrollbarSide:
+        return mPrefScrollbarSide;
+      case kPresContext_BidiDirection:
+        return mPrefBidiDirection;
+      default:
+        NS_ERROR("invalid arg passed to GetCachedIntPref");
+    }
+
+    return false;
+  }
+
+  const mozilla::PreferenceSheet::Prefs& PrefSheetPrefs() const {
+    return mozilla::PreferenceSheet::PrefsFor(*mDocument);
+  }
+  nscolor DefaultBackgroundColor() const {
+    return PrefSheetPrefs().mDefaultBackgroundColor;
+  }
+
+  nsISupports* GetContainerWeak() const;
+
+  nsDocShell* GetDocShell() const;
+
+  /**
+   * Get the visible area associated with this presentation context.
+   * This is the size of the visible area that is used for
+   * presenting the document. The returned value is in the standard
+   * nscoord units (as scaled by the device context).
+   */
+  nsRect GetVisibleArea() const { return mVisibleArea; }
+
+  /**
+   * Set the currently visible area. The units for r are standard
+   * nscoord units (as scaled by the device context).
+   */
+  void SetVisibleArea(const nsRect& r);
+
+  nsSize GetSizeForViewportUnits() const { return mSizeForViewportUnits; }
+
+  /**
+   * Set the maximum height of the dynamic toolbar in nscoord units.
+   */
+  MOZ_CAN_RUN_SCRIPT
+  void SetDynamicToolbarMaxHeight(mozilla::ScreenIntCoord aHeight);
+
+  mozilla::ScreenIntCoord GetDynamicToolbarMaxHeight() const {
+    MOZ_ASSERT(IsRootContentDocumentCrossProcess());
+    return mDynamicToolbarMaxHeight;
+  }
+
+  /**
+   * Returns true if we are using the dynamic toolbar.
+   */
+  bool HasDynamicToolbar() const {
+    MOZ_ASSERT(IsRootContentDocumentCrossProcess());
+    return mDynamicToolbarMaxHeight > 0;
+  }
+
+  /*
+   * |aOffset| must be offset from the bottom edge of the ICB and it's negative.
+   */
+  void UpdateDynamicToolbarOffset(mozilla::ScreenIntCoord aOffset);
+  mozilla::ScreenIntCoord GetDynamicToolbarHeight() const {
+    MOZ_ASSERT(IsRootContentDocumentCrossProcess());
+    return mDynamicToolbarHeight;
+  }
+
+  /**
+   * Returns the state of the dynamic toolbar.
+   */
+  mozilla::DynamicToolbarState GetDynamicToolbarState() const;
+
+  /**
+   * Return true if this presentation context is a paginated
+   * context.
+   */
+  bool IsPaginated() const { return mPaginated; }
+
+  /**
+   * Sets whether the presentation context can scroll for a paginated
+   * context.
+   */
+  void SetPaginatedScrolling(bool aResult);
+
+  /**
+   * Return true if this presentation context can scroll for paginated
+   * context.
+   */
+  bool HasPaginatedScrolling() const { return mCanPaginatedScroll; }
+
+  /**
+   * Get/set the size of a page
+   */
+  const nsSize& GetPageSize() const { return mPageSize; }
+  const nsMargin& GetDefaultPageMargin() const { return mDefaultPageMargin; }
+  void SetPageSize(nsSize aSize) { mPageSize = aSize; }
+
+  /**
+   * Get/set whether this document should be treated as having real pages
+   * XXX This raises the obvious question of why a document that isn't a page
+   *     is paginated; there isn't a good reason except history
+   */
+  bool IsRootPaginatedDocument() { return mIsRootPaginatedDocument; }
+  void SetIsRootPaginatedDocument(bool aIsRootPaginatedDocument) {
+    mIsRootPaginatedDocument = aIsRootPaginatedDocument;
+  }
+
+  /**
+   * Get/set the print scaling level; used by nsPageFrame to scale up
+   * pages.  Set safe to call before reflow, get guaranteed to be set
+   * properly after reflow.
+   */
+
+  float GetPageScale() { return mPageScale; }
+  void SetPageScale(float aScale) { mPageScale = aScale; }
+
+  /**
+   * Get/set the scaling factor to use when rendering the pages for print
+   * preview. Only safe to get after print preview set up; safe to set anytime.
+   * This is a scaling factor for the display of the print preview.  It
+   * does not affect layout.  It only affects the size of the onscreen pages
+   * in print preview.
+   *
+   * The getter should only be used by the page sequence frame, which is the
+   * frame responsible for applying the scaling. Other callers should use
+   * nsPageSequenceFrame::GetPrintPreviewScale() if needed, instead of this API.
+   *
+   * XXX Temporary: see http://wiki.mozilla.org/Gecko:PrintPreview
+   */
+  float GetPrintPreviewScaleForSequenceFrame() { return mPPScale; }
+  void SetPrintPreviewScale(float aScale) { mPPScale = aScale; }
+
+  nsDeviceContext* DeviceContext() const { return mDeviceContext; }
+  mozilla::EventStateManager* EventStateManager() { return mEventManager; }
+
+  /**
+   * Get/set a text zoom factor that is applied on top of the normal text zoom
+   * set by the front-end/user.
+   */
+  float GetSystemFontScale() const { return mSystemFontScale; }
+  void SetSystemFontScale(float aFontScale) {
+    MOZ_ASSERT(aFontScale > 0.0f, "invalid font scale");
+    if (aFontScale == mSystemFontScale || IsPrintingOrPrintPreview()) {
+      return;
+    }
+
+    mSystemFontScale = aFontScale;
+    UpdateEffectiveTextZoom();
+  }
+
+  /**
+   * Get/set the text zoom factor in use.
+   * This value should be used if you're interested in the pure text zoom value
+   * controlled by the front-end, e.g. when transferring zoom levels to a new
+   * document.
+   * Code that wants to use this value for layouting and rendering purposes
+   * should consider using EffectiveTextZoom() instead, so as to take the system
+   * font scale into account as well.
+   */
+  float TextZoom() const { return mTextZoom; }
+
+  /**
+   * Corresponds to the product of text zoom and system font scale, limited
+   * by zoom.maxPercent and minPercent.
+   * As the system font scale is automatically set by the PresShell, code that
+   * e.g. wants to transfer zoom levels to a new document should use TextZoom()
+   * instead, which corresponds to the text zoom level that was actually set by
+   * the front-end/user.
+   */
+  float EffectiveTextZoom() const { return mEffectiveTextZoom; }
+
+  /**
+   * Notify the pres context that the safe area insets have changed.
+   */
+  void SetSafeAreaInsets(const mozilla::ScreenIntMargin& aInsets);
+
+  mozilla::ScreenIntMargin GetSafeAreaInsets() const { return mSafeAreaInsets; }
+
+  bool RegisterOneShotPostRefreshObserver(
+      mozilla::OneShotPostRefreshObserver* aObserver);
+  void UnregisterOneShotPostRefreshObserver(
+      mozilla::OneShotPostRefreshObserver* aObserver);
+  void ClearOneShotPostRefreshObservers();
+
+ protected:
+  void UpdateEffectiveTextZoom();
+
+#ifdef DEBUG
+  void ValidatePresShellAndDocumentReleation() const;
+#endif  // #ifdef DEBUG
+
+  void SetTextZoom(float aZoom) {
+    MOZ_ASSERT(aZoom > 0.0f, "invalid zoom factor");
+    if (aZoom == mTextZoom) return;
+
+    mTextZoom = aZoom;
+    UpdateEffectiveTextZoom();
+  }
+  void SetFullZoom(float aZoom);
+
+ public:
+  float GetFullZoom() { return mFullZoom; }
+  /**
+   * Device full zoom differs from full zoom because it gets the zoom from
+   * the device context, which may be using a different zoom due to rounding
+   * of app units to device pixels.
+   */
+  float GetDeviceFullZoom();
+
+  float GetOverrideDPPX() const { return mMediaEmulationData.mDPPX; }
+  void SetOverrideDPPX(float);
+
+  /**
+   * Recomputes the data dependent on the browsing context, like zoom and text
+   * zoom.
+   *
+   * TODO(emilio): Eventually stuff like the media emulation data, overrideDPPX
+   * and such should also move here.
+   */
+  void RecomputeBrowsingContextDependentData();
+
+  Maybe<StylePrefersColorScheme> GetOverridePrefersColorScheme() const {
+    return mMediaEmulationData.mPrefersColorScheme;
+  }
+  void SetOverridePrefersColorScheme(const Maybe<StylePrefersColorScheme>&);
+
+  mozilla::CSSCoord GetAutoQualityMinFontSize() const {
+    return DevPixelsToFloatCSSPixels(mAutoQualityMinFontSizePixelsPref);
+  }
+
+  /**
+   * Return the device's screen size in inches, for font size
+   * inflation.
+   *
+   * If |aChanged| is non-null, then aChanged is filled in with whether
+   * the screen size value has changed since either:
+   *  a. the last time the function was called with non-null aChanged, or
+   *  b. the first time the function was called.
+   */
+  gfxSize ScreenSizeInchesForFontInflation(bool* aChanged = nullptr);
+
+  int32_t AppUnitsPerDevPixel() const { return mCurAppUnitsPerDevPixel; }
+
+  static nscoord CSSPixelsToAppUnits(int32_t aPixels) {
+    return NSToCoordRoundWithClamp(float(aPixels) *
+                                   float(mozilla::AppUnitsPerCSSPixel()));
+  }
+
+  static nscoord CSSPixelsToAppUnits(float aPixels) {
+    return NSToCoordRoundWithClamp(aPixels *
+                                   float(mozilla::AppUnitsPerCSSPixel()));
+  }
+
+  static int32_t AppUnitsToIntCSSPixels(nscoord aAppUnits) {
+    return NSAppUnitsToIntPixels(aAppUnits,
+                                 float(mozilla::AppUnitsPerCSSPixel()));
+  }
+
+  static float AppUnitsToFloatCSSPixels(nscoord aAppUnits) {
+    return NSAppUnitsToFloatPixels(aAppUnits,
+                                   float(mozilla::AppUnitsPerCSSPixel()));
+  }
+
+  static double AppUnitsToDoubleCSSPixels(nscoord aAppUnits) {
+    return NSAppUnitsToDoublePixels(aAppUnits,
+                                    double(mozilla::AppUnitsPerCSSPixel()));
+  }
+
+  nscoord DevPixelsToAppUnits(int32_t aPixels) const {
+    return NSIntPixelsToAppUnits(aPixels, AppUnitsPerDevPixel());
+  }
+
+  int32_t AppUnitsToDevPixels(nscoord aAppUnits) const {
+    return NSAppUnitsToIntPixels(aAppUnits, float(AppUnitsPerDevPixel()));
+  }
+
+  float AppUnitsToFloatDevPixels(nscoord aAppUnits) {
+    return aAppUnits / float(AppUnitsPerDevPixel());
+  }
+
+  int32_t CSSPixelsToDevPixels(int32_t aPixels) {
+    return AppUnitsToDevPixels(CSSPixelsToAppUnits(aPixels));
+  }
+
+  float CSSPixelsToDevPixels(float aPixels) {
+    return NSAppUnitsToFloatPixels(CSSPixelsToAppUnits(aPixels),
+                                   float(AppUnitsPerDevPixel()));
+  }
+
+  int32_t DevPixelsToIntCSSPixels(int32_t aPixels) {
+    return AppUnitsToIntCSSPixels(DevPixelsToAppUnits(aPixels));
+  }
+
+  float DevPixelsToFloatCSSPixels(int32_t aPixels) const {
+    return AppUnitsToFloatCSSPixels(DevPixelsToAppUnits(aPixels));
+  }
+
+  mozilla::CSSToLayoutDeviceScale CSSToDevPixelScale() const {
+    return mozilla::CSSToLayoutDeviceScale(
+        float(mozilla::AppUnitsPerCSSPixel()) / float(AppUnitsPerDevPixel()));
+  }
+
+  // If there is a remainder, it is rounded to nearest app units.
+  nscoord GfxUnitsToAppUnits(gfxFloat aGfxUnits) const;
+
+  gfxFloat AppUnitsToGfxUnits(nscoord aAppUnits) const;
+
+  gfxRect AppUnitsToGfxUnits(const nsRect& aAppRect) const {
+    return gfxRect(AppUnitsToGfxUnits(aAppRect.x),
+                   AppUnitsToGfxUnits(aAppRect.y),
+                   AppUnitsToGfxUnits(aAppRect.Width()),
+                   AppUnitsToGfxUnits(aAppRect.Height()));
+  }
+
+  static nscoord CSSTwipsToAppUnits(float aTwips) {
+    return NSToCoordRoundWithClamp(mozilla::AppUnitsPerCSSInch() *
+                                   NS_TWIPS_TO_INCHES(aTwips));
+  }
+
+  // Margin-specific version, since they often need TwipsToAppUnits
+  static nsMargin CSSTwipsToAppUnits(const nsIntMargin& marginInTwips) {
+    return nsMargin(CSSTwipsToAppUnits(float(marginInTwips.top)),
+                    CSSTwipsToAppUnits(float(marginInTwips.right)),
+                    CSSTwipsToAppUnits(float(marginInTwips.bottom)),
+                    CSSTwipsToAppUnits(float(marginInTwips.left)));
+  }
+
+  static nscoord CSSPointsToAppUnits(float aPoints) {
+    return NSToCoordRound(aPoints * mozilla::AppUnitsPerCSSInch() /
+                          POINTS_PER_INCH_FLOAT);
+  }
+
+  nscoord PhysicalMillimetersToAppUnits(float aMM) const;
+
+  nscoord RoundAppUnitsToNearestDevPixels(nscoord aAppUnits) const {
+    return DevPixelsToAppUnits(AppUnitsToDevPixels(aAppUnits));
+  }
+
+  /**
+   * This checks the root element and the HTML BODY, if any, for an "overflow"
+   * property that should be applied to the viewport. If one is found then we
+   * return the element that we took the overflow from (which should then be
+   * treated as "overflow: visible"), and we store the overflow style here.
+   * If the document is in fullscreen, and the fullscreen element is not the
+   * root, the scrollbar of viewport will be suppressed.
+   * @return if scroll was propagated from some content node, the content node
+   *         it was propagated from.
+   */
+  mozilla::dom::Element* UpdateViewportScrollStylesOverride();
+
+  /**
+   * Returns the cached result from the last call to
+   * UpdateViewportScrollStylesOverride() -- i.e. return the node
+   * whose scrollbar styles we have propagated to the viewport (or nullptr if
+   * there is no such node).
+   */
+  mozilla::dom::Element* GetViewportScrollStylesOverrideElement() const {
+    return mViewportScrollOverrideElement;
+  }
+
+  const ScrollStyles& GetViewportScrollStylesOverride() const {
+    return mViewportScrollStyles;
+  }
+
+  /**
+   * Check whether the given element would propagate its scrollbar styles to the
+   * viewport in non-paginated mode.
+   */
+  bool ElementWouldPropagateScrollStyles(const mozilla::dom::Element&);
+
+  /**
+   * Methods for controlling the background drawing.
+   */
+  bool GetBackgroundImageDraw() const { return mDrawImageBackground; }
+  bool GetBackgroundColorDraw() const { return mDrawColorBackground; }
+
+  /**
+   *  Check if bidi enabled (set depending on the presence of RTL
+   *  characters or when default directionality is RTL).
+   *  If enabled, we should apply the Unicode Bidi Algorithm
+   *
+   *  @lina 07/12/2000
+   */
+  bool BidiEnabled() const;
+
+  /**
+   *  Set bidi enabled. This means we should apply the Unicode Bidi Algorithm
+   *
+   *  @lina 07/12/2000
+   */
+  void SetBidiEnabled() const;
+
+  /**
+   *  Set visual or implicit mode into the pres context.
+   *
+   *  Visual directionality is a presentation method that displays text
+   *  as if it were a uni-directional, according to the primary display
+   *  direction only.
+   *
+   *  Implicit directionality is a presentation method in which the
+   *  direction is determined by the Bidi algorithm according to the
+   *  category of the characters and the category of the adjacent
+   *  characters, and according to their primary direction.
+   *
+   *  @lina 05/02/2000
+   */
+  void SetVisualMode(bool aIsVisual) { mIsVisual = aIsVisual; }
+
+  /**
+   *  Check whether the content should be treated as visual.
+   *
+   *  @lina 05/02/2000
+   */
+  bool IsVisualMode() const { return mIsVisual; }
+
+  enum class InteractionType : uint32_t {
+    ClickInteraction,
+    KeyInteraction,
+    MouseMoveInteraction,
+    ScrollInteraction
+  };
+
+  void RecordInteractionTime(InteractionType aType,
+                             const mozilla::TimeStamp& aTimeStamp);
+
+  void DisableInteractionTimeRecording() { mInteractionTimeEnabled = false; }
+
+  // Mohamed
+
+  /**
+   * Set the Bidi options for the presentation context
+   */
+  void SetBidi(uint32_t aBidiOptions);
+
+  /**
+   * Get the Bidi options for the presentation context
+   * Not inline so consumers of nsPresContext are not forced to
+   * include Document.
+   */
+  uint32_t GetBidi() const;
+
+  /*
+   * Obtain a native theme for rendering our widgets (both form controls and
+   * html)
+   *
+   * Guaranteed to return non-null.
+   */
+  nsITheme* Theme() MOZ_NONNULL_RETURN {
+    if (MOZ_LIKELY(mTheme)) {
+      return mTheme;
+    }
+    return EnsureTheme();
+  }
+
+  /*
+   * Notify the pres context that the theme has changed.  An internal switch
+   * means it's one of our Mozilla themes that changed (e.g., Modern to
+   * Classic). Otherwise, the OS is telling us that the native theme for the
+   * platform has changed.
+   */
+  void ThemeChanged(mozilla::widget::ThemeChangeKind);
+
+  /*
+   * Notify the pres context that the resolution of the user interface has
+   * changed. This happens if a window is moved between HiDPI and non-HiDPI
+   * displays, so that the ratio of points to device pixels changes.
+   * The notification happens asynchronously.
+   */
+  void UIResolutionChanged();
+
+  /*
+   * Like UIResolutionChanged() but invalidates values immediately.
+   */
+  void UIResolutionChangedSync();
+
+  /** Printing methods below should only be used for Medium() == print **/
+  void SetPrintSettings(nsIPrintSettings* aPrintSettings);
+
+  nsIPrintSettings* GetPrintSettings() { return mPrintSettings; }
+
+  /* Helper function that ensures that this prescontext is shown in its
+     docshell if it's the most recent prescontext for the docshell.  Returns
+     whether the prescontext is now being shown.
+  */
+  bool EnsureVisible();
+
+#ifdef MOZ_REFLOW_PERF
+  void CountReflows(const char* aName, nsIFrame* aFrame);
+#endif
+
+  void ConstructedFrame() { ++mFramesConstructed; }
+  void ReflowedFrame() { ++mFramesReflowed; }
+
+  uint64_t FramesConstructedCount() { return mFramesConstructed; }
+  uint64_t FramesReflowedCount() { return mFramesReflowed; }
+
+  static nscoord GetBorderWidthForKeyword(unsigned int aBorderWidthKeyword) {
+    // This table maps border-width enums 'thin', 'medium', 'thick'
+    // to actual nscoord values.
+    static const nscoord kBorderWidths[] = {
+        CSSPixelsToAppUnits(1), CSSPixelsToAppUnits(3), CSSPixelsToAppUnits(5)};
+    MOZ_ASSERT(size_t(aBorderWidthKeyword) <
+               mozilla::ArrayLength(kBorderWidths));
+
+    return kBorderWidths[aBorderWidthKeyword];
+  }
+
+  gfxTextPerfMetrics* GetTextPerfMetrics() { return mTextPerf.get(); }
+  FontMatchingStats* GetFontMatchingStats() { return mFontStats.get(); }
+
+  bool IsDynamic() {
+    return (mType == eContext_PageLayout || mType == eContext_Galley);
+  }
+  bool IsScreen() {
+    return (mMedium == nsGkAtoms::screen || mType == eContext_PageLayout ||
+            mType == eContext_PrintPreview);
+  }
+  bool IsPrintingOrPrintPreview() {
+    return (mType == eContext_Print || mType == eContext_PrintPreview);
+  }
+
+  // Is this presentation in a chrome docshell?
+  bool IsChrome() const;
+
+  // Public API for native theme code to get style internals.
+  bool HasAuthorSpecifiedRules(const nsIFrame* aFrame,
+                               uint32_t ruleTypeMask) const;
+
+  // Explicitly enable and disable paint flashing.
+  void SetPaintFlashing(bool aPaintFlashing) {
+    mPaintFlashing = aPaintFlashing;
+    mPaintFlashingInitialized = true;
+  }
+
+  // This method should be used instead of directly accessing mPaintFlashing,
+  // as that value may be out of date when mPaintFlashingInitialized is false.
+  bool GetPaintFlashing() const;
+
+  bool SuppressingResizeReflow() const { return mSuppressResizeReflow; }
+
+  gfxUserFontSet* GetUserFontSet();
+
+  // Should be called whenever the set of fonts available in the user
+  // font set changes (e.g., because a new font loads, or because the
+  // user font set is changed and fonts become unavailable).
+  void UserFontSetUpdated(gfxUserFontEntry* aUpdatedFont = nullptr);
+
+  gfxMissingFontRecorder* MissingFontRecorder() { return mMissingFonts.get(); }
+
+  void NotifyMissingFonts();
+
+  void FlushCounterStyles();
+  void MarkCounterStylesDirty();
+
+  void FlushFontFeatureValues();
+  void MarkFontFeatureValuesDirty() { mFontFeatureValuesDirty = true; }
+
+  // Ensure that it is safe to hand out CSS rules outside the layout
+  // engine by ensuring that all CSS style sheets have unique inners
+  // and, if necessary, synchronously rebuilding all style data.
+  void EnsureSafeToHandOutCSSRules();
+
+  // Mark an area as invalidated, associated with a given transaction id
+  // (allocated by nsRefreshDriver::GetTransactionId). Invalidated regions will
+  // be dispatched to MozAfterPaint events when NotifyDidPaintForSubtree is
+  // called for the transaction id (or any higher id).
+  void NotifyInvalidation(TransactionId aTransactionId, const nsRect& aRect);
+  // aRect is in device pixels
+  void NotifyInvalidation(TransactionId aTransactionId, const nsIntRect& aRect);
+  void NotifyDidPaintForSubtree(
+      TransactionId aTransactionId = TransactionId{0},
+      const mozilla::TimeStamp& aTimeStamp = mozilla::TimeStamp());
+  void NotifyRevokingDidPaint(TransactionId aTransactionId);
+  void FireDOMPaintEvent(nsTArray<nsRect>* aList, TransactionId aTransactionId,
+                         mozilla::TimeStamp aTimeStamp = mozilla::TimeStamp());
+
+  // Callback for catching invalidations in ContainerLayers
+  // Passed to LayerProperties::ComputeDifference
+  static void NotifySubDocInvalidation(
+      mozilla::layers::ContainerLayer* aContainer, const nsIntRegion* aRegion);
+  void SetNotifySubDocInvalidationData(
+      mozilla::layers::ContainerLayer* aContainer);
+  static void ClearNotifySubDocInvalidationData(
+      mozilla::layers::ContainerLayer* aContainer);
+  bool IsDOMPaintEventPending();
+
+  /**
+   * Returns the RestyleManager's restyle generation counter.
+   */
+  uint64_t GetRestyleGeneration() const;
+  uint64_t GetUndisplayedRestyleGeneration() const;
+
+  /**
+   * Returns whether there are any pending restyles or reflows.
+   */
+  bool HasPendingRestyleOrReflow();
+
+  /**
+   * Notify the prescontext that the presshell is about to reflow a reflow root.
+   * The single argument indicates whether this reflow should be interruptible.
+   * If aInterruptible is false then CheckForInterrupt and HasPendingInterrupt
+   * will always return false. If aInterruptible is true then CheckForInterrupt
+   * will return true when a pending event is detected.  This is for use by the
+   * presshell only.  Reflow code wanting to prevent interrupts should use
+   * InterruptPreventer.
+   */
+  void ReflowStarted(bool aInterruptible);
+
+  /**
+   * A class that can be used to temporarily disable reflow interruption.
+   */
+  class InterruptPreventer;
+  friend class InterruptPreventer;
+  class MOZ_STACK_CLASS InterruptPreventer {
+   public:
+    explicit InterruptPreventer(nsPresContext* aCtx)
+        : mCtx(aCtx),
+          mInterruptsEnabled(aCtx->mInterruptsEnabled),
+          mHasPendingInterrupt(aCtx->mHasPendingInterrupt) {
+      mCtx->mInterruptsEnabled = false;
+      mCtx->mHasPendingInterrupt = false;
+    }
+    ~InterruptPreventer() {
+      mCtx->mInterruptsEnabled = mInterruptsEnabled;
+      mCtx->mHasPendingInterrupt = mHasPendingInterrupt;
+    }
+
+   private:
+    nsPresContext* mCtx;
+    bool mInterruptsEnabled;
+    bool mHasPendingInterrupt;
+  };
+
+  /**
+   * Check for interrupts. This may return true if a pending event is
+   * detected. Once it has returned true, it will keep returning true
+   * until ReflowStarted is called. In all cases where this returns true,
+   * the passed-in frame (which should be the frame whose reflow will be
+   * interrupted if true is returned) will be passed to
+   * PresShell::FrameNeedsToContinueReflow.
+   */
+  bool CheckForInterrupt(nsIFrame* aFrame);
+  /**
+   * Returns true if CheckForInterrupt has returned true since the last
+   * ReflowStarted call. Cannot itself trigger an interrupt check.
+   */
+  bool HasPendingInterrupt() { return mHasPendingInterrupt; }
+  /**
+   * Sets a flag that will trip a reflow interrupt. This only bypasses the
+   * interrupt timeout and the pending event check; other checks such as whether
+   * interrupts are enabled and the interrupt check skipping still take effect.
+   */
+  void SetPendingInterruptFromTest() { mPendingInterruptFromTest = true; }
+
+  /**
+   * If we have a presshell, and if the given content's current
+   * document is the same as our presshell's document, return the
+   * content's primary frame.  Otherwise, return null.  Only use this
+   * if you care about which presshell the primary frame is in.
+   */
+  nsIFrame* GetPrimaryFrameFor(nsIContent* aContent);
+
+  virtual size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+  virtual size_t SizeOfIncludingThis(
+      mozilla::MallocSizeOf aMallocSizeOf) const {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  /**
+   * Deprecated. Please use the InProcess or CrossProcess variants
+   * to specify which behaviour you want.
+   */
+  bool IsRootContentDocument() const;
+
+  /**
+   * We are a root content document in process if: we are not a resource doc, we
+   * are not chrome, and we either have no parent in the current process or our
+   * parent is chrome.
+   */
+  bool IsRootContentDocumentInProcess() const;
+
+  /**
+   * We are a root content document cross process if: we are not a resource doc,
+   * we are not chrome, and we either have no parent in any process or our
+   * parent is chrome.
+   */
+  bool IsRootContentDocumentCrossProcess() const;
+
+  bool HadNonBlankPaint() const { return mHadNonBlankPaint; }
+  bool HadContentfulPaint() const { return mHadContentfulPaint; }
+  void NotifyNonBlankPaint();
+  void NotifyContentfulPaint();
+  void NotifyPaintStatusReset();
+  void NotifyDOMContentFlushed();
+
+  bool HasEverBuiltInvisibleText() const { return mHasEverBuiltInvisibleText; }
+  void SetBuiltInvisibleText() { mHasEverBuiltInvisibleText = true; }
+
+  bool UsesExChUnits() const { return mUsesExChUnits; }
+
+  void SetUsesExChUnits(bool aValue) { mUsesExChUnits = aValue; }
+
+  bool IsDeviceSizePageSize();
+
+  bool HasWarnedAboutPositionedTableParts() const {
+    return mHasWarnedAboutPositionedTableParts;
+  }
+
+  void SetHasWarnedAboutPositionedTableParts() {
+    mHasWarnedAboutPositionedTableParts = true;
+  }
+
+  bool HasWarnedAboutTooLargeDashedOrDottedRadius() const {
+    return mHasWarnedAboutTooLargeDashedOrDottedRadius;
+  }
+
+  void SetHasWarnedAboutTooLargeDashedOrDottedRadius() {
+    mHasWarnedAboutTooLargeDashedOrDottedRadius = true;
+  }
+
+  nsBidi& GetBidiEngine();
+
+  gfxFontFeatureValueSet* GetFontFeatureValuesLookup() const {
+    return mFontFeatureValuesLookup;
+  }
+
+ protected:
+  friend class nsRunnableMethod<nsPresContext>;
+  void ThemeChangedInternal();
+  void RefreshSystemMetrics();
+
+  // update device context's resolution from the widget
+  void UIResolutionChangedInternal();
+
+  // if aScale > 0.0, use it as resolution scale factor to the device context
+  // (otherwise get it from the widget)
+  void UIResolutionChangedInternalScale(double aScale);
+
+  void SetImgAnimations(nsIContent* aParent, uint16_t aMode);
+  void SetSMILAnimations(mozilla::dom::Document* aDoc, uint16_t aNewMode,
+                         uint16_t aOldMode);
+
+  static void PreferenceChanged(const char* aPrefName, void* aSelf);
+  void PreferenceChanged(const char* aPrefName);
+
+  void UpdateAfterPreferencesChanged();
+  void DispatchPrefChangedRunnableIfNeeded();
+
+  void GetUserPreferences();
+
+  void UpdateCharSet(NotNull<const Encoding*> aCharSet);
+
+ public:
+  // Used by the PresShell to force a reflow when some aspect of font info
+  // has been updated, potentially affecting font selection and layout.
+  void ForceReflowForFontInfoUpdate();
+
+  /**
+   * Checks for MozAfterPaint listeners on the document
+   */
+  bool MayHavePaintEventListener();
+
+  /**
+   * Checks for MozAfterPaint listeners on the document and
+   * any subdocuments, except for subdocuments that are non-top-level
+   * content documents.
+   */
+  bool MayHavePaintEventListenerInSubDocument();
+
+  void InvalidatePaintedLayers();
+
+  uint32_t GetNextFrameRateMultiplier() const {
+    return mNextFrameRateMultiplier;
+  }
+
+  void DidUseFrameRateMultiplier() {
+    if (!mNextFrameRateMultiplier) {
+      mNextFrameRateMultiplier = 1;
+    } else if (mNextFrameRateMultiplier < 8) {
+      mNextFrameRateMultiplier = mNextFrameRateMultiplier * 2;
+    }
+  }
+
+ protected:
+  // May be called multiple times (unlink, destructor)
+  void Destroy();
+
+  void AppUnitsPerDevPixelChanged();
+
+  bool HavePendingInputEvent();
+
+  // Creates a one-shot timer with the given aCallback & aDelay.
+  // Returns a refcounted pointer to the timer (or nullptr on failure).
+  already_AddRefed<nsITimer> CreateTimer(nsTimerCallbackFunc aCallback,
+                                         const char* aName, uint32_t aDelay);
+
+  struct TransactionInvalidations {
+    TransactionId mTransactionId;
+    nsTArray<nsRect> mInvalidations;
+    bool mIsWaitingForPreviousTransaction = false;
+  };
+  TransactionInvalidations* GetInvalidations(TransactionId aTransactionId);
+
+  // This should be called only when we update mVisibleArea or
+  // mDynamicToolbarMaxHeight or `app units per device pixels` changes.
+  void AdjustSizeForViewportUnits();
+
+  // IMPORTANT: The ownership implicit in the following member variables
+  // has been explicitly checked.  If you add any members to this class,
+  // please make the ownership explicit (pinkerton, scc).
+
+  // the PresShell owns a strong reference to the nsPresContext, and is
+  // responsible for nulling this pointer before it is destroyed
+  mozilla::PresShell* MOZ_NON_OWNING_REF mPresShell;  // [WEAK]
+  RefPtr<mozilla::dom::Document> mDocument;
+  RefPtr<nsDeviceContext> mDeviceContext;  // [STRONG] could be weak, but
+                                           // better safe than sorry.
+                                           // Cannot reintroduce cycles
+                                           // since there is no dependency
+                                           // from gfx back to layout.
+  RefPtr<mozilla::EventStateManager> mEventManager;
+  RefPtr<nsRefreshDriver> mRefreshDriver;
+  RefPtr<mozilla::AnimationEventDispatcher> mAnimationEventDispatcher;
+  RefPtr<mozilla::EffectCompositor> mEffectCompositor;
+  mozilla::UniquePtr<nsTransitionManager> mTransitionManager;
+  mozilla::UniquePtr<nsAnimationManager> mAnimationManager;
+  mozilla::UniquePtr<mozilla::RestyleManager> mRestyleManager;
+  RefPtr<mozilla::CounterStyleManager> mCounterStyleManager;
+  const nsStaticAtom* mMedium;
+  RefPtr<gfxFontFeatureValueSet> mFontFeatureValuesLookup;
+
+  // TODO(emilio): Maybe lazily create and put under a UniquePtr if this grows a
+  // lot?
+  MediaEmulationData mMediaEmulationData;
+
+  float mSystemFontScale;    // Internal text zoom factor, defaults to 1.0
+  float mTextZoom;           // Text zoom, defaults to 1.0
+  float mEffectiveTextZoom;  // Text zoom * system font scale
+  float mFullZoom;           // Page zoom, defaults to 1.0
+  gfxSize mLastFontInflationScreenSize;
+
+  int32_t mCurAppUnitsPerDevPixel;
+  int32_t mAutoQualityMinFontSizePixelsPref;
+
+  nsCOMPtr<nsITheme> mTheme;
+  nsCOMPtr<nsIPrintSettings> mPrintSettings;
+
+  mozilla::UniquePtr<nsBidi> mBidiEngine;
+
+  AutoTArray<TransactionInvalidations, 4> mTransactions;
+
+  // text performance metrics
+  mozilla::UniquePtr<gfxTextPerfMetrics> mTextPerf;
+
+  mozilla::UniquePtr<FontMatchingStats> mFontStats;
+
+  mozilla::UniquePtr<gfxMissingFontRecorder> mMissingFonts;
+
+  nsRect mVisibleArea;
+  // This value is used to resolve viewport units.
+  // On mobile this size is including the dynamic toolbar maximum height below.
+  // On desktops this size is pretty much the same as |mVisibleArea|.
+  nsSize mSizeForViewportUnits;
+  // The maximum height of the dynamic toolbar on mobile.
+  mozilla::ScreenIntCoord mDynamicToolbarMaxHeight;
+  mozilla::ScreenIntCoord mDynamicToolbarHeight;
+  // Safe area insets support
+  mozilla::ScreenIntMargin mSafeAreaInsets;
+  nsSize mPageSize;
+
+  // The computed page margins from the print settings.
+  //
+  // This margin will be used for each page in the current print operation, by
+  // default (i.e. unless overridden by @page rules).
+  //
+  // FIXME(emilio): Maybe we could let a global @page rule do that, though it's
+  // sketchy at best, see https://github.com/w3c/csswg-drafts/issues/5437 for
+  // discussion.
+  nsMargin mDefaultPageMargin;
+  float mPageScale;
+  float mPPScale;
+
+  // This is a non-owning pointer. May be null. If non-null, it's guaranteed to
+  // be pointing to an element that's still alive, because we'll reset it in
+  // UpdateViewportScrollStylesOverride() as part of the cleanup code when
+  // this element is removed from the document. (For <body> and the root
+  // element, this call happens in nsCSSFrameConstructor::ContentRemoved(). For
+  // fullscreen elements, it happens in the fullscreen-specific cleanup invoked
+  // by Element::UnbindFromTree().)
+  mozilla::dom::Element* MOZ_NON_OWNING_REF mViewportScrollOverrideElement;
+
+  // Counters for tests and tools that want to detect frame construction
+  // or reflow.
+  uint64_t mElementsRestyled;
+  uint64_t mFramesConstructed;
+  uint64_t mFramesReflowed;
+
+  mozilla::TimeStamp mReflowStartTime;
+
+  Maybe<TransactionId> mFirstContentfulPaintTransactionId;
+
+  mozilla::UniquePtr<mozilla::MediaFeatureChange>
+      mPendingMediaFeatureValuesChange;
+
+  // Time of various first interaction types, used to report time from
+  // first paint of the top level content pres shell to first interaction.
+  mozilla::TimeStamp mFirstNonBlankPaintTime;
+  mozilla::TimeStamp mFirstClickTime;
+  mozilla::TimeStamp mFirstKeyTime;
+  mozilla::TimeStamp mFirstMouseMoveTime;
+  mozilla::TimeStamp mFirstScrollTime;
+
+  // last time we did a full style flush
+  mozilla::TimeStamp mLastStyleUpdateForAllAnimations;
+
+  nsChangeHint mChangeHintForPrefChange;
+
+  uint32_t mInterruptChecksToSkip;
+
+  // During page load we use slower frame rate.
+  uint32_t mNextFrameRateMultiplier;
+
+  nsTArray<RefPtr<mozilla::OneShotPostRefreshObserver>>
+      mOneShotPostRefreshObservers;
+
+  ScrollStyles mViewportScrollStyles;
+
+  uint16_t mImageAnimationMode;
+  uint16_t mImageAnimationModePref;
+
+  nsPresContextType mType;
+
+ public:
+  // The following are public member variables so that we can use them
+  // with mozilla::AutoToggle or mozilla::AutoRestore.
+
+  // Should we disable font size inflation because we're inside of
+  // shrink-wrapping calculations on an inflation container?
+  bool mInflationDisabledForShrinkWrap;
+
+ protected:
+  static constexpr size_t kThemeChangeKindBits = 2;
+  static_assert(unsigned(mozilla::widget::ThemeChangeKind::AllBits) <=
+                    (1u << kThemeChangeKindBits) - 1,
+                "theme change kind doesn't fit");
+
+  unsigned mInteractionTimeEnabled : 1;
+  unsigned mHasPendingInterrupt : 1;
+  unsigned mHasEverBuiltInvisibleText : 1;
+  unsigned mPendingInterruptFromTest : 1;
+  unsigned mInterruptsEnabled : 1;
+  unsigned mSendAfterPaintToContent : 1;
+  unsigned mDrawImageBackground : 1;
+  unsigned mDrawColorBackground : 1;
+  unsigned mNeverAnimate : 1;
+  unsigned mPaginated : 1;
+  unsigned mCanPaginatedScroll : 1;
+  unsigned mDoScaledTwips : 1;
+  unsigned mIsRootPaginatedDocument : 1;
+  unsigned mPrefBidiDirection : 1;
+  unsigned mPrefScrollbarSide : 2;
+  unsigned mPendingThemeChanged : 1;
+  // widget::ThemeChangeKind
+  unsigned mPendingThemeChangeKind : kThemeChangeKindBits;
+  unsigned mPendingUIResolutionChanged : 1;
+  unsigned mPostedPrefChangedRunnable : 1;
+
+  // Are we currently drawing an SVG glyph?
+  unsigned mIsGlyph : 1;
+
+  // Does the associated document use ex or ch units?
+  //
+  // TODO(emilio): It's a bit weird that this lives here but all the other
+  // relevant bits live in Device on the rust side.
+  unsigned mUsesExChUnits : 1;
+
+  // Is the current mCounterStyleManager valid?
+  unsigned mCounterStylesDirty : 1;
+
+  // Is the current mFontFeatureValuesLookup valid?
+  unsigned mFontFeatureValuesDirty : 1;
+
+  // resize reflow is suppressed when the only change has been to zoom
+  // the document rather than to change the document's dimensions
+  unsigned mSuppressResizeReflow : 1;
+
+  unsigned mIsVisual : 1;
+
+  // Should we paint flash in this context? Do not use this variable directly.
+  // Use GetPaintFlashing() method instead.
+  mutable unsigned mPaintFlashing : 1;
+  mutable unsigned mPaintFlashingInitialized : 1;
+
+  unsigned mHasWarnedAboutPositionedTableParts : 1;
+
+  unsigned mHasWarnedAboutTooLargeDashedOrDottedRadius : 1;
+
+  // Have we added quirk.css to the style set?
+  unsigned mQuirkSheetAdded : 1;
+
+  // Has NotifyNonBlankPaint been called on this PresContext?
+  unsigned mHadNonBlankPaint : 1;
+  // Has NotifyContentfulPaint been called on this PresContext?
+  unsigned mHadContentfulPaint : 1;
+  // Has NotifyDidPaintForSubtree been called for a contentful paint?
+  unsigned mHadContentfulPaintComposite : 1;
+
+#ifdef DEBUG
+  unsigned mInitialized : 1;
+#endif
+
+ protected:
+  virtual ~nsPresContext();
+
+  void LastRelease();
+
+  nsITheme* EnsureTheme();
+
+#ifdef DEBUG
+ private:
+  friend struct nsAutoLayoutPhase;
+  mozilla::EnumeratedArray<nsLayoutPhase, nsLayoutPhase::COUNT, uint32_t>
+      mLayoutPhaseCount;
+
+ public:
+  uint32_t LayoutPhaseCount(nsLayoutPhase aPhase) {
+    return mLayoutPhaseCount[aPhase];
+  }
+#endif
+};
+
+class nsRootPresContext final : public nsPresContext {
+ public:
+  nsRootPresContext(mozilla::dom::Document* aDocument, nsPresContextType aType);
+  virtual ~nsRootPresContext();
+
+  /**
+   * Registers a plugin to receive geometry updates (position and clip
+   * region) so it can update its widget.
+   * Callers must call UnregisterPluginForGeometryUpdates before
+   * the aPlugin frame is destroyed.
+   */
+  void RegisterPluginForGeometryUpdates(nsIContent* aPlugin);
+  /**
+   * Stops a plugin receiving geometry updates (position and clip
+   * region). If the plugin was not already registered, this does
+   * nothing.
+   */
+  void UnregisterPluginForGeometryUpdates(nsIContent* aPlugin);
+
+  bool NeedToComputePluginGeometryUpdates() {
+    return mRegisteredPlugins.Count() > 0;
+  }
+  /**
+   * Compute geometry updates for each plugin given that aList is the display
+   * list for aFrame. The updates are not yet applied;
+   * ApplyPluginGeometryUpdates is responsible for that. In the meantime they
+   * are stored on each nsPluginFrame.
+   * This needs to be called even when aFrame is a popup, since although
+   * windowed plugins aren't allowed in popups, windowless plugins are
+   * and ComputePluginGeometryUpdates needs to be called for them.
+   * aBuilder and aList can be null. This indicates that all plugins are
+   * hidden because we're in a background tab.
+   */
+  void ComputePluginGeometryUpdates(nsIFrame* aFrame,
+                                    nsDisplayListBuilder* aBuilder,
+                                    nsDisplayList* aList);
+
+  /**
+   * Apply the stored plugin geometry updates. This should normally be called
+   * in DidPaint so the plugins are moved/clipped immediately after we've
+   * updated our window, so they look in sync with our window.
+   */
+  void ApplyPluginGeometryUpdates();
+
+  /**
+   * Transfer stored plugin geometry updates to the compositor. Called during
+   * reflow, data is shipped over with layer updates. e10s specific.
+   */
+  void CollectPluginGeometryUpdates(
+      mozilla::layers::LayerManager* aLayerManager);
+
+  virtual bool IsRoot() override { return true; }
+
+  /**
+   * Add a runnable that will get called before the next paint. They will get
+   * run eventually even if painting doesn't happen. They might run well before
+   * painting happens.
+   */
+  void AddWillPaintObserver(nsIRunnable* aRunnable);
+
+  /**
+   * Run all runnables that need to get called before the next paint.
+   */
+  void FlushWillPaintObservers();
+
+  virtual size_t SizeOfExcludingThis(
+      mozilla::MallocSizeOf aMallocSizeOf) const override;
+
+ protected:
+  /**
+   * Start a timer to ensure we eventually run ApplyPluginGeometryUpdates.
+   */
+  void InitApplyPluginGeometryTimer();
+  /**
+   * Cancel the timer that ensures we eventually run ApplyPluginGeometryUpdates.
+   */
+  void CancelApplyPluginGeometryTimer();
+
+  class RunWillPaintObservers : public mozilla::Runnable {
+   public:
+    explicit RunWillPaintObservers(nsRootPresContext* aPresContext)
+        : Runnable("nsPresContextType::RunWillPaintObservers"),
+          mPresContext(aPresContext) {}
+    void Revoke() { mPresContext = nullptr; }
+    NS_IMETHOD Run() override {
+      if (mPresContext) {
+        mPresContext->FlushWillPaintObservers();
+      }
+      return NS_OK;
+    }
+    // The lifetime of this reference is handled by an nsRevocableEventPtr
+    nsRootPresContext* MOZ_NON_OWNING_REF mPresContext;
+  };
+
+  friend class nsPresContext;
+
+  nsCOMPtr<nsITimer> mApplyPluginGeometryTimer;
+  nsTHashtable<nsRefPtrHashKey<nsIContent>> mRegisteredPlugins;
+  nsTArray<nsCOMPtr<nsIRunnable>> mWillPaintObservers;
+  nsRevocableEventPtr<RunWillPaintObservers> mWillPaintFallbackEvent;
+};
+
+#ifdef MOZ_REFLOW_PERF
+
+#  define DO_GLOBAL_REFLOW_COUNT(_name) \
+    aPresContext->CountReflows((_name), (nsIFrame*)this);
+#else
+#  define DO_GLOBAL_REFLOW_COUNT(_name)
+#endif  // MOZ_REFLOW_PERF
+
+#endif /* nsPresContext_h___ */