Bug 1488684 - Made nsIFrame-derived classes and some others 'final' where possible - r=dbaron

All classes deriving from nsIFrame that did not have any subclasses themselves
(at the time of writing this patch) have been marked with `final`.
Some other Layout classes have also been made final, but this was opportunistic
while working on nsIFrame subclasses, and is definitely not exhaustive, further
patches welcome; refer to bug 1332680.

Advantages of marking a class final include:
- Allowing the compiler to devirtualize some method calls (i.e., calling
  virtual functions directly instead of going through the vtable),
- Indicating that the class is not currently subclassed,
- Preventing subclassing without being aware that this would remove the
  finalization benefits of the parent class.
`final` does not signify that these classes should *never* be subclassed, this
is left for developers to decide.

Differential Revision: https://phabricator.services.mozilla.com/D5020

--HG--
extra : moz-landing-system : lando

layout/base/nsDocumentViewer.cpp

@@ -148,7 +148,7 @@ class AutoPrintEventDispatcher;
 
 // a small delegate class used to avoid circular references
 
-class nsDocViewerSelectionListener : public nsISelectionListener
+class nsDocViewerSelectionListener final : public nsISelectionListener
 {
 public:
 
@@ -180,7 +180,7 @@ protected:
 
 /** editor Implementation of the FocusListener interface
  */
-class nsDocViewerFocusListener : public nsIDOMEventListener
+class nsDocViewerFocusListener final : public nsIDOMEventListener
 {
 public:
   /** default constructor

layout/base/nsFrameTraversal.h

@@ -22,7 +22,7 @@ nsresult NS_NewFrameTraversal(nsIFrameEnumerator **aEnumerator,
 
 nsresult NS_CreateFrameTraversal(nsIFrameTraversal** aResult);
 
-class nsFrameTraversal : public nsIFrameTraversal
+class nsFrameTraversal final : public nsIFrameTraversal
 {
 public:
   nsFrameTraversal();

layout/base/nsPresContext.cpp

@@ -2174,7 +2174,7 @@ nsPresContext::UserFontSetUpdated(gfxUserFontEntry* aUpdatedFont)
   }
 }
 
-class CounterStyleCleaner : public nsAPostRefreshObserver
+class CounterStyleCleaner final : public nsAPostRefreshObserver
 {
 public:
   CounterStyleCleaner(nsRefreshDriver* aRefreshDriver,

layout/build/nsContentDLF.h

@@ -19,7 +19,7 @@ class nsIStreamListener;
 #define CONTENT_DLF_CONTRACTID "@mozilla.org/content/document-loader-factory;1"
 #define PLUGIN_DLF_CONTRACTID "@mozilla.org/content/plugin/document-loader-factory;1"
 
-class nsContentDLF : public nsIDocumentLoaderFactory
+class nsContentDLF final : public nsIDocumentLoaderFactory
 {
 protected:
   virtual ~nsContentDLF();

layout/forms/nsButtonFrameRenderer.cpp

@@ -211,7 +211,8 @@ nsDisplayButtonBoxShadowOuter::CreateWebRenderCommands(
   return true;
 }
 
-class nsDisplayButtonBorder : public nsDisplayItem {
+class nsDisplayButtonBorder final : public nsDisplayItem
+{
 public:
   nsDisplayButtonBorder(nsDisplayListBuilder* aBuilder,
                                   nsButtonFrameRenderer* aRenderer)
@@ -334,7 +335,8 @@ nsDisplayButtonBorder::GetBounds(nsDisplayListBuilder* aBuilder,
           : mFrame->GetVisualOverflowRectRelativeToSelf() + ToReferenceFrame();
 }
 
-class nsDisplayButtonForeground : public nsDisplayItem {
+class nsDisplayButtonForeground final : public nsDisplayItem
+{
 public:
   nsDisplayButtonForeground(nsDisplayListBuilder* aBuilder,
                             nsButtonFrameRenderer* aRenderer)

layout/forms/nsComboboxControlFrame.cpp

@@ -89,7 +89,7 @@ nsComboboxControlFrame::RedisplayTextEvent::Run()
  * combo box is toggled to open or close. this is used by Accessibility which presses
  * that button Programmatically.
  */
-class nsComboButtonListener : public nsIDOMEventListener
+class nsComboButtonListener final : public nsIDOMEventListener
 {
 private:
   virtual ~nsComboButtonListener() {}
@@ -1304,7 +1304,8 @@ nsComboboxControlFrame::GetDisplayNode() const
 
 // XXXbz this is a for-now hack.  Now that display:inline-block works,
 // need to revisit this.
-class nsComboboxDisplayFrame : public nsBlockFrame {
+class nsComboboxDisplayFrame final : public nsBlockFrame
+{
 public:
   NS_DECL_FRAMEARENA_HELPERS(nsComboboxDisplayFrame)
 
@@ -1554,7 +1555,8 @@ nsComboboxControlFrame::UpdateRecentIndex(int32_t aIndex)
   return index;
 }
 
-class nsDisplayComboboxFocus : public nsDisplayItem {
+class nsDisplayComboboxFocus : public nsDisplayItem
+{
 public:
   nsDisplayComboboxFocus(nsDisplayListBuilder* aBuilder,
                          nsComboboxControlFrame* aFrame)

layout/forms/nsFieldSetFrame.cpp

@@ -79,7 +79,8 @@ nsFieldSetFrame::GetLegend() const
   return mFrames.FirstChild();
 }
 
-class nsDisplayFieldSetBorder : public nsDisplayItem {
+class nsDisplayFieldSetBorder final : public nsDisplayItem
+{
 public:
   nsDisplayFieldSetBorder(nsDisplayListBuilder* aBuilder,
                           nsFieldSetFrame* aFrame)

layout/forms/nsFileControlFrame.h

@@ -22,9 +22,9 @@ class DataTransfer;
 } // namespace dom
 } // namespace mozilla
 
-class nsFileControlFrame : public nsBlockFrame,
-                           public nsIFormControlFrame,
-                           public nsIAnonymousContentCreator
+class nsFileControlFrame final : public nsBlockFrame,
+                                 public nsIFormControlFrame,
+                                 public nsIAnonymousContentCreator
 {
 public:
   explicit nsFileControlFrame(ComputedStyle* aStyle);

layout/forms/nsImageControlFrame.cpp

@@ -16,8 +16,8 @@
 
 using namespace mozilla;
 
-class nsImageControlFrame : public nsImageFrame,
-                            public nsIFormControlFrame
+class nsImageControlFrame final : public nsImageFrame,
+                                  public nsIFormControlFrame
 {
 public:
   explicit nsImageControlFrame(ComputedStyle* aStyle);

layout/forms/nsMeterFrame.h

@@ -13,8 +13,8 @@
 #include "nsCOMPtr.h"
 #include "nsCSSPseudoElements.h"
 
-class nsMeterFrame : public nsContainerFrame,
-                     public nsIAnonymousContentCreator
+class nsMeterFrame final : public nsContainerFrame,
+                           public nsIAnonymousContentCreator
 
 {
   typedef mozilla::dom::Element Element;

layout/forms/nsRangeFrame.cpp

@@ -163,7 +163,7 @@ nsRangeFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
   }
 }
 
-class nsDisplayRangeFocusRing : public nsDisplayItem
+class nsDisplayRangeFocusRing final : public nsDisplayItem
 {
 public:
   nsDisplayRangeFocusRing(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame)

layout/forms/nsSelectsAreaFrame.h

@@ -9,7 +9,7 @@
 #include "mozilla/Attributes.h"
 #include "nsBlockFrame.h"
 
-class nsSelectsAreaFrame : public nsBlockFrame
+class nsSelectsAreaFrame final : public nsBlockFrame
 {
 public:
   NS_DECL_FRAMEARENA_HELPERS(nsSelectsAreaFrame)

layout/generic/ScrollAnimationBezierPhysics.h

@@ -25,7 +25,7 @@ struct ScrollAnimationBezierPhysicsSettings
 
 // This class implements a cubic bezier timing function and automatically
 // adapts the animation duration based on the scrolling rate.
-class ScrollAnimationBezierPhysics : public ScrollAnimationPhysics
+class ScrollAnimationBezierPhysics final : public ScrollAnimationPhysics
 {
 public:
   explicit ScrollAnimationBezierPhysics(const nsPoint& aStartPos,

layout/generic/ScrollAnimationMSDPhysics.h

@@ -14,7 +14,7 @@ namespace mozilla {
 
 // This class implements a cubic MSD timing function and automatically
 // adapts the animation duration based on the scrolling rate.
-class ScrollAnimationMSDPhysics : public ScrollAnimationPhysics
+class ScrollAnimationMSDPhysics final : public ScrollAnimationPhysics
 {
 public:
   typedef mozilla::layers::AxisPhysicsMSDModel AxisPhysicsMSDModel;

layout/generic/TextOverflow.cpp

@@ -162,7 +162,7 @@ IsFrameDescendantOfAny(nsIFrame* aChild,
   return false;
 }
 
-class nsDisplayTextOverflowMarker : public nsDisplayItem
+class nsDisplayTextOverflowMarker final : public nsDisplayItem
 {
 public:
   nsDisplayTextOverflowMarker(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,

layout/generic/ViewportFrame.h

@@ -26,7 +26,8 @@ class ServoRestyleState;
   * containing the doc root frame. ViewportFrame stores this child in its primary child
   * list.
   */
-class ViewportFrame : public nsContainerFrame {
+class ViewportFrame : public nsContainerFrame
+{
 public:
   NS_DECL_QUERYFRAME
   NS_DECL_FRAMEARENA_HELPERS(ViewportFrame)

layout/generic/nsCanvasFrame.h

@@ -144,7 +144,8 @@ private:
  * We can also paint an "extra background color" behind the normal
  * background.
  */
-class nsDisplayCanvasBackgroundColor : public nsDisplaySolidColorBase {
+class nsDisplayCanvasBackgroundColor final : public nsDisplaySolidColorBase
+{
 public:
   nsDisplayCanvasBackgroundColor(nsDisplayListBuilder* aBuilder, nsIFrame *aFrame)
     : nsDisplaySolidColorBase(aBuilder, aFrame, NS_RGBA(0,0,0,0))

layout/generic/nsFrameSetFrame.h

@@ -62,7 +62,7 @@ struct nsFramesetDrag {
 /*******************************************************************************
  * nsHTMLFramesetFrame
  ******************************************************************************/
-class nsHTMLFramesetFrame : public nsContainerFrame
+class nsHTMLFramesetFrame final : public nsContainerFrame
 {
 public:
   NS_DECL_QUERYFRAME

layout/generic/nsHTMLCanvasFrame.cpp

@@ -63,7 +63,8 @@ IntrinsicRatioFromCanvasSize(const nsIntSize& aCanvasSizeInPx)
                 nsPresContext::CSSPixelsToAppUnits(aCanvasSizeInPx.height));
 }
 
-class nsDisplayCanvas : public nsDisplayItem {
+class nsDisplayCanvas final : public nsDisplayItem
+{
 public:
   nsDisplayCanvas(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame)
     : nsDisplayItem(aBuilder, aFrame)

layout/generic/nsImageFrame.cpp

@@ -1382,7 +1382,8 @@ struct nsRecessedBorder : public nsStyleBorder {
   }
 };
 
-class nsDisplayAltFeedback : public nsDisplayItem {
+class nsDisplayAltFeedback final : public nsDisplayItem
+{
 public:
   nsDisplayAltFeedback(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame)
     : nsDisplayItem(aBuilder, aFrame) {}

layout/generic/nsImageFrame.h

@@ -42,7 +42,7 @@ namespace layers {
 } // namespace layers
 } // namespace mozilla
 
-class nsImageListener : public imgINotificationObserver
+class nsImageListener final : public imgINotificationObserver
 {
 protected:
   virtual ~nsImageListener();
@@ -446,7 +446,8 @@ public:
  * image itself, and hence receive events just as if the image itself
  * received events.
  */
-class nsDisplayImage : public nsDisplayImageContainer {
+class nsDisplayImage final : public nsDisplayImageContainer
+{
 public:
   typedef mozilla::layers::LayerManager LayerManager;
 

layout/generic/nsImageMap.cpp

@@ -268,7 +268,8 @@ void Area::HasFocus(bool aHasFocus)
 
 //----------------------------------------------------------------------
 
-class DefaultArea : public Area {
+class DefaultArea final : public Area
+{
 public:
   explicit DefaultArea(HTMLAreaElement* aArea);
 
@@ -312,7 +313,8 @@ void DefaultArea::GetRect(nsIFrame* aFrame, nsRect& aRect)
 
 //----------------------------------------------------------------------
 
-class RectArea : public Area {
+class RectArea final : public Area
+{
 public:
   explicit RectArea(HTMLAreaElement* aArea);
 
@@ -418,7 +420,8 @@ void RectArea::GetRect(nsIFrame* aFrame, nsRect& aRect)
 
 //----------------------------------------------------------------------
 
-class PolyArea : public Area {
+class PolyArea final : public Area
+{
 public:
   explicit PolyArea(HTMLAreaElement* aArea);
 
@@ -575,7 +578,8 @@ void PolyArea::GetRect(nsIFrame* aFrame, nsRect& aRect)
 
 //----------------------------------------------------------------------
 
-class CircleArea : public Area {
+class CircleArea final : public Area
+{
 public:
   explicit CircleArea(HTMLAreaElement* aArea);
 

layout/generic/nsPageFrame.cpp

@@ -474,7 +474,8 @@ static gfx::Matrix4x4 ComputePageTransform(nsIFrame* aFrame, float aAppUnitsPerP
   return gfx::Matrix4x4::Scaling(scale, scale, 1);
 }
 
-class nsDisplayHeaderFooter : public nsDisplayItem {
+class nsDisplayHeaderFooter final : public nsDisplayItem
+{
 public:
   nsDisplayHeaderFooter(nsDisplayListBuilder* aBuilder, nsPageFrame *aFrame)
     : nsDisplayItem(aBuilder, aFrame)

layout/generic/nsPluginFrame.h

@@ -363,7 +363,8 @@ public:
   }
 };
 
-class nsDisplayPlugin : public nsDisplayItem {
+class nsDisplayPlugin final : public nsDisplayItem
+{
 public:
   nsDisplayPlugin(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame)
     : nsDisplayItem(aBuilder, aFrame)

layout/generic/nsTextFrame.cpp

@@ -196,7 +196,8 @@ NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(FontSizeInflationProperty, float)
  *
  * This is stored in {Simple, Complex}TextRunUserData.
  */
-class GlyphObserver : public gfxFont::GlyphChangeObserver {
+class GlyphObserver final : public gfxFont::GlyphChangeObserver
+{
 public:
   GlyphObserver(gfxFont* aFont, gfxTextRun* aTextRun)
     : gfxFont::GlyphChangeObserver(aFont), mTextRun(aTextRun) {
@@ -4884,7 +4885,8 @@ nsTextFrame::CharacterDataChanged(const CharacterDataChangeInfo& aInfo)
   return NS_OK;
 }
 
-class nsDisplayText final : public nsCharClipDisplayItem {
+class nsDisplayText final : public nsCharClipDisplayItem
+{
 public:
   nsDisplayText(nsDisplayListBuilder* aBuilder, nsTextFrame* aFrame,
                 const Maybe<bool>& aIsSelected);

layout/generic/nsVideoFrame.h

@@ -26,8 +26,8 @@ class LayerManager;
 class nsPresContext;
 class nsDisplayItem;
 
-class nsVideoFrame : public nsContainerFrame
-                   , public nsIAnonymousContentCreator
+class nsVideoFrame final : public nsContainerFrame
+                         , public nsIAnonymousContentCreator
 {
 public:
   template <typename T> using Maybe = mozilla::Maybe<T>;

layout/ipc/RenderFrameParent.h

@@ -32,7 +32,7 @@ struct ScrollableLayerGuid;
 
 namespace layout {
 
-class RenderFrameParent : public PRenderFrameParent
+class RenderFrameParent final : public PRenderFrameParent
 {
   typedef mozilla::layers::AsyncDragMetrics AsyncDragMetrics;
   typedef mozilla::layers::FrameMetrics FrameMetrics;
@@ -144,7 +144,7 @@ private:
  * layer tree (for a given RenderFrameParent) into its parent
  * process's layer tree.
  */
-class nsDisplayRemote : public nsDisplayItem
+class nsDisplayRemote final : public nsDisplayItem
 {
   typedef mozilla::layout::RenderFrameParent RenderFrameParent;
 

layout/mathml/nsMathMLChar.cpp

@@ -1830,7 +1830,7 @@ nsMathMLChar::GetMaxWidth(nsIFrame* aForFrame,
   return std::max(bm.width, bm.rightBearing) - std::min(0, bm.leftBearing);
 }
 
-class nsDisplayMathMLSelectionRect : public nsDisplayItem {
+class nsDisplayMathMLSelectionRect final : public nsDisplayItem {
 public:
   nsDisplayMathMLSelectionRect(nsDisplayListBuilder* aBuilder,
                                nsIFrame* aFrame, const nsRect& aRect)
@@ -1864,7 +1864,7 @@ void nsDisplayMathMLSelectionRect::Paint(nsDisplayListBuilder* aBuilder,
   drawTarget->FillRect(rect, ColorPattern(ToDeviceColor(bgColor)));
 }
 
-class nsDisplayMathMLCharForeground : public nsDisplayItem {
+class nsDisplayMathMLCharForeground final : public nsDisplayItem {
 public:
   nsDisplayMathMLCharForeground(nsDisplayListBuilder* aBuilder,
                                 nsIFrame* aFrame, nsMathMLChar* aChar,
@@ -1920,7 +1920,7 @@ private:
 };
 
 #ifdef DEBUG
-class nsDisplayMathMLCharDebug : public nsDisplayItem {
+class nsDisplayMathMLCharDebug final : public nsDisplayItem {
 public:
   nsDisplayMathMLCharDebug(nsDisplayListBuilder* aBuilder,
                            nsIFrame* aFrame, const nsRect& aRect)

layout/mathml/nsMathMLContainerFrame.h

@@ -401,7 +401,8 @@ private:
 // 2) proper inter-frame spacing
 // 3) firing of Stretch() (in which case FinalizeReflow() would have to be cleaned)
 // Issues: If/when mathml becomes a pluggable component, the separation will be needed.
-class nsMathMLmathBlockFrame : public nsBlockFrame {
+class nsMathMLmathBlockFrame final : public nsBlockFrame
+{
 public:
   NS_DECL_QUERYFRAME
   NS_DECL_FRAMEARENA_HELPERS(nsMathMLmathBlockFrame)
@@ -483,8 +484,9 @@ protected:
 
 // --------------
 
-class nsMathMLmathInlineFrame : public nsInlineFrame,
-                                public nsMathMLFrame {
+class nsMathMLmathInlineFrame final : public nsInlineFrame,
+                                      public nsMathMLFrame
+{
 public:
   NS_DECL_QUERYFRAME
   NS_DECL_FRAMEARENA_HELPERS(nsMathMLmathInlineFrame)

layout/mathml/nsMathMLFrame.cpp

@@ -276,7 +276,7 @@ nsMathMLFrame::ParseNumericValue(const nsString&   aString,
 }
 
 #if defined(DEBUG) && defined(SHOW_BOUNDING_BOX)
-class nsDisplayMathMLBoundingMetrics : public nsDisplayItem {
+class nsDisplayMathMLBoundingMetrics final : public nsDisplayItem {
 public:
   nsDisplayMathMLBoundingMetrics(nsDisplayListBuilder* aBuilder,
                                  nsIFrame* aFrame, const nsRect& aRect)
@@ -324,7 +324,8 @@ nsMathMLFrame::DisplayBoundingMetrics(nsDisplayListBuilder* aBuilder,
 }
 #endif
 
-class nsDisplayMathMLBar : public nsDisplayItem {
+class nsDisplayMathMLBar final : public nsDisplayItem
+{
 public:
   nsDisplayMathMLBar(nsDisplayListBuilder* aBuilder,
                      nsIFrame* aFrame, const nsRect& aRect, uint32_t aIndex)

layout/mathml/nsMathMLmactionFrame.h

@@ -16,7 +16,8 @@
 // <maction> -- bind actions to a subexpression
 //
 
-class nsMathMLmactionFrame : public nsMathMLSelectedFrame {
+class nsMathMLmactionFrame final : public nsMathMLSelectedFrame
+{
 public:
   NS_DECL_FRAMEARENA_HELPERS(nsMathMLmactionFrame)
 

layout/mathml/nsMathMLmencloseFrame.cpp

@@ -747,7 +747,7 @@ nsMathMLmencloseFrame::SetAdditionalComputedStyle(int32_t          aIndex,
     mMathMLChar[aIndex].SetComputedStyle(aComputedStyle);
 }
 
-class nsDisplayNotation : public nsDisplayItem
+class nsDisplayNotation final : public nsDisplayItem
 {
 public:
   nsDisplayNotation(nsDisplayListBuilder* aBuilder,

layout/mathml/nsMathMLmfracFrame.h

@@ -50,7 +50,8 @@ environment, but can be set explicitly only on the <mstyle>
 element.
 */
 
-class nsMathMLmfracFrame : public nsMathMLContainerFrame {
+class nsMathMLmfracFrame final : public nsMathMLContainerFrame
+{
 public:
   NS_DECL_FRAMEARENA_HELPERS(nsMathMLmfracFrame)
 

layout/mathml/nsMathMLmmultiscriptsFrame.h

@@ -17,7 +17,8 @@
 // <msup> -- attach a superscript to a base
 //
 
-class nsMathMLmmultiscriptsFrame : public nsMathMLContainerFrame {
+class nsMathMLmmultiscriptsFrame final : public nsMathMLContainerFrame
+{
 public:
   NS_DECL_FRAMEARENA_HELPERS(nsMathMLmmultiscriptsFrame)
 

layout/mathml/nsMathMLmoFrame.h

@@ -15,7 +15,8 @@
 // <mo> -- operator, fence, or separator
 //
 
-class nsMathMLmoFrame : public nsMathMLTokenFrame {
+class nsMathMLmoFrame final : public nsMathMLTokenFrame
+{
 public:
   NS_DECL_FRAMEARENA_HELPERS(nsMathMLmoFrame)
 

layout/mathml/nsMathMLmpaddedFrame.h

@@ -14,7 +14,8 @@
 // <mpadded> -- adjust space around content
 //
 
-class nsMathMLmpaddedFrame : public nsMathMLContainerFrame {
+class nsMathMLmpaddedFrame final : public nsMathMLContainerFrame
+{
 public:
   NS_DECL_FRAMEARENA_HELPERS(nsMathMLmpaddedFrame)
 

layout/mathml/nsMathMLmrootFrame.h

@@ -15,7 +15,8 @@
 // <msqrt> and <mroot> -- form a radical
 //
 
-class nsMathMLmrootFrame : public nsMathMLContainerFrame {
+class nsMathMLmrootFrame final : public nsMathMLContainerFrame
+{
 public:
   NS_DECL_FRAMEARENA_HELPERS(nsMathMLmrootFrame)
 

layout/mathml/nsMathMLmrowFrame.h

@@ -16,7 +16,8 @@
 // <mstyle> -- make style changes that affect the rendering of its contents
 //
 
-class nsMathMLmrowFrame : public nsMathMLContainerFrame {
+class nsMathMLmrowFrame final : public nsMathMLContainerFrame
+{
 public:
   NS_DECL_FRAMEARENA_HELPERS(nsMathMLmrowFrame)
 

layout/mathml/nsMathMLmspaceFrame.h

@@ -14,7 +14,8 @@
 // <mspace> -- space
 //
 
-class nsMathMLmspaceFrame : public nsMathMLContainerFrame {
+class nsMathMLmspaceFrame final : public nsMathMLContainerFrame
+{
 public:
   NS_DECL_FRAMEARENA_HELPERS(nsMathMLmspaceFrame)
 

layout/mathml/nsMathMLmsqrtFrame.h

@@ -33,7 +33,8 @@ These attributes are inherited by every element from its rendering environment,
 but can be set explicitly only on <mstyle>. (See Section 3.3.4.)
 */
 
-class nsMathMLmsqrtFrame : public nsMathMLmencloseFrame {
+class nsMathMLmsqrtFrame final : public nsMathMLmencloseFrame
+{
 public:
   NS_DECL_FRAMEARENA_HELPERS(nsMathMLmsqrtFrame)
 

layout/mathml/nsMathMLmtableFrame.cpp

@@ -262,7 +262,7 @@ ComputeBorderOverflow(nsMathMLmtdFrame* aFrame,
  * around a nsMathMLmtdFrame based on the rowline and columnline properties
  * set on the cell frame.
  */
-class nsDisplaymtdBorder : public nsDisplayBorder
+class nsDisplaymtdBorder final : public nsDisplayBorder
 {
 public:
   nsDisplaymtdBorder(nsDisplayListBuilder* aBuilder, nsMathMLmtdFrame* aFrame)

layout/mathml/nsMathMLmtableFrame.h

@@ -242,7 +242,7 @@ protected:
 
 // --------------
 
-class nsMathMLmtdFrame : public nsTableCellFrame
+class nsMathMLmtdFrame final : public nsTableCellFrame
 {
 public:
   NS_DECL_FRAMEARENA_HELPERS(nsMathMLmtdFrame)

layout/mathml/nsMathMLsemanticsFrame.h

@@ -14,7 +14,8 @@
 // <semantics> -- associate annotations with a MathML expression
 //
 
-class nsMathMLsemanticsFrame : public nsMathMLSelectedFrame {
+class nsMathMLsemanticsFrame final : public nsMathMLSelectedFrame
+{
 public:
   NS_DECL_FRAMEARENA_HELPERS(nsMathMLsemanticsFrame)
 

layout/printing/DrawEventRecorder.h

@@ -16,7 +16,8 @@
 namespace mozilla {
 namespace layout {
 
-class PRFileDescStream : public mozilla::gfx::EventStream {
+class PRFileDescStream final : public mozilla::gfx::EventStream
+{
   // Most writes, as seen in the print IPC use case, are very small (<32 bytes),
   // with a small number of very large (>40KB) writes. Writes larger than this
   // value are not buffered.
@@ -129,7 +130,7 @@ private:
   bool mGood;
 };
 
-class DrawEventRecorderPRFileDesc : public gfx::DrawEventRecorderPrivate
+class DrawEventRecorderPRFileDesc final : public gfx::DrawEventRecorderPrivate
 {
 public:
   MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(DrawEventRecorderPRFileDesc, override)

layout/style/nsFontFaceLoader.h

@@ -22,8 +22,8 @@
 
 class nsIPrincipal;
 
-class nsFontFaceLoader : public nsIStreamLoaderObserver
-                       , public nsIRequestObserver
+class nsFontFaceLoader final : public nsIStreamLoaderObserver
+                             , public nsIRequestObserver
 {
 public:
   nsFontFaceLoader(gfxUserFontEntry* aFontToLoad, nsIURI* aFontURI,

layout/svg/SVGFEContainerFrame.cpp

@@ -18,7 +18,7 @@ using namespace mozilla;
  * This frame is used by filter primitive elements that
  * have special child elements that provide parameters.
  */
-class SVGFEContainerFrame : public nsContainerFrame
+class SVGFEContainerFrame final : public nsContainerFrame
 {
   friend nsIFrame*
   NS_NewSVGFEContainerFrame(nsIPresShell* aPresShell, ComputedStyle* aStyle);

layout/svg/SVGFEUnstyledLeafFrame.cpp

@@ -11,7 +11,7 @@
 #include "SVGObserverUtils.h"
 #include "nsSVGFilters.h"
 
-class SVGFEUnstyledLeafFrame : public nsFrame
+class SVGFEUnstyledLeafFrame final : public nsFrame
 {
   friend nsIFrame*
   NS_NewSVGFEUnstyledLeafFrame(nsIPresShell* aPresShell, ComputedStyle* aStyle);

layout/svg/SVGGeometryFrame.cpp

@@ -57,7 +57,8 @@ NS_QUERYFRAME_TAIL_INHERITING(nsFrame)
 //----------------------------------------------------------------------
 // Display list item:
 
-class nsDisplaySVGGeometry : public nsDisplayItem {
+class nsDisplaySVGGeometry final : public nsDisplayItem
+{
   typedef mozilla::image::imgDrawingParams imgDrawingParams;
 
 public:

layout/svg/SVGTextFrame.cpp

@@ -2724,7 +2724,8 @@ CharIterator::MatchesFilter() const
  * An nsCharClipDisplayItem that obtains its left and right clip edges from a
  * TextRenderedRun object.
  */
-class SVGCharClipDisplayItem : public nsCharClipDisplayItem {
+class SVGCharClipDisplayItem final : public nsCharClipDisplayItem
+{
 public:
   explicit SVGCharClipDisplayItem(const TextRenderedRun& aRun)
     : nsCharClipDisplayItem(aRun.mFrame)
@@ -2747,7 +2748,7 @@ public:
  * cannot be done directly (e.g. if we are using an SVG pattern fill, stroking
  * the text, etc.).
  */
-class SVGTextDrawPathCallbacks : public nsTextFrame::DrawPathCallbacks
+class SVGTextDrawPathCallbacks final : public nsTextFrame::DrawPathCallbacks
 {
   typedef mozilla::image::imgDrawingParams imgDrawingParams;
 
@@ -3066,7 +3067,8 @@ SVGTextDrawPathCallbacks::StrokeGeometry()
 // ----------------------------------------------------------------------------
 // Display list item
 
-class nsDisplaySVGText : public nsDisplayItem {
+class nsDisplaySVGText final : public nsDisplayItem
+{
 public:
   nsDisplaySVGText(nsDisplayListBuilder* aBuilder, SVGTextFrame* aFrame)
     : nsDisplayItem(aBuilder, aFrame)

layout/svg/SVGViewFrame.cpp

@@ -19,7 +19,7 @@ using namespace mozilla::dom;
  * identifier. The SVGViewFrame class passes on any attribute changes
  * the view receives to the overridden <svg> element (if there is one).
  **/
-class SVGViewFrame : public nsFrame
+class SVGViewFrame final : public nsFrame
 {
   friend nsIFrame*
   NS_NewSVGViewFrame(nsIPresShell* aPresShell, ComputedStyle* aStyle);

layout/svg/nsSVGAFrame.cpp

@@ -16,7 +16,7 @@
 
 using namespace mozilla;
 
-class nsSVGAFrame : public nsSVGDisplayContainerFrame
+class nsSVGAFrame final : public nsSVGDisplayContainerFrame
 {
   friend nsIFrame*
   NS_NewSVGAFrame(nsIPresShell* aPresShell, ComputedStyle* aStyle);

layout/svg/nsSVGFilterFrame.h

@@ -27,7 +27,7 @@ class SVGFilterElement;
 } // namespace dom
 } // namespace mozilla
 
-class nsSVGFilterFrame : public nsSVGContainerFrame
+class nsSVGFilterFrame final : public nsSVGContainerFrame
 {
   friend nsIFrame*
   NS_NewSVGFilterFrame(nsIPresShell* aPresShell, ComputedStyle* aStyle);

layout/svg/nsSVGForeignObjectFrame.h

@@ -17,8 +17,8 @@
 
 class gfxContext;
 
-class nsSVGForeignObjectFrame : public nsContainerFrame
-                              , public nsSVGDisplayableFrame
+class nsSVGForeignObjectFrame final : public nsContainerFrame
+                                    , public nsSVGDisplayableFrame
 {
   friend nsContainerFrame*
   NS_NewSVGForeignObjectFrame(nsIPresShell* aPresShell, ComputedStyle* aStyle);

layout/svg/nsSVGGradientFrame.h

@@ -119,7 +119,7 @@ private:
 // Linear Gradients
 // -------------------------------------------------------------------------
 
-class nsSVGLinearGradientFrame : public nsSVGGradientFrame
+class nsSVGLinearGradientFrame final : public nsSVGGradientFrame
 {
   friend nsIFrame* NS_NewSVGLinearGradientFrame(nsIPresShell* aPresShell,
                                                 ComputedStyle* aStyle);
@@ -161,7 +161,7 @@ protected:
 // Radial Gradients
 // -------------------------------------------------------------------------
 
-class nsSVGRadialGradientFrame : public nsSVGGradientFrame
+class nsSVGRadialGradientFrame final : public nsSVGGradientFrame
 {
   friend nsIFrame* NS_NewSVGRadialGradientFrame(nsIPresShell* aPresShell,
                                                 ComputedStyle* aStyle);

layout/svg/nsSVGOuterSVGFrame.cpp

@@ -539,7 +539,8 @@ nsSVGOuterSVGFrame::UnionChildOverflow(nsOverflowAreas& aOverflowAreas)
 /**
  * Used to paint/hit-test SVG when SVG display lists are disabled.
  */
-class nsDisplayOuterSVG : public nsDisplayItem {
+class nsDisplayOuterSVG final : public nsDisplayItem
+{
 public:
   nsDisplayOuterSVG(nsDisplayListBuilder* aBuilder,
                     nsSVGOuterSVGFrame* aFrame) :

layout/svg/nsSVGSymbolFrame.h

@@ -9,8 +9,7 @@
 
 #include "nsSVGViewportFrame.h"
 
-class nsSVGSymbolFrame
- : public nsSVGViewportFrame
+class nsSVGSymbolFrame final : public nsSVGViewportFrame
 {
   friend nsIFrame*
   NS_NewSVGSymbolFrame(nsIPresShell* aPresShell, ComputedStyle* aStyle);

layout/xul/nsMenuPopupFrame.h

@@ -141,8 +141,8 @@ class nsView;
 class nsMenuPopupFrame;
 
 // this class is used for dispatching popupshown events asynchronously.
-class nsXULPopupShownEvent : public mozilla::Runnable,
-                             public nsIDOMEventListener
+class nsXULPopupShownEvent final : public mozilla::Runnable,
+                                   public nsIDOMEventListener
 {
 public:
   nsXULPopupShownEvent(nsIContent* aPopup, nsPresContext* aPresContext)

layout/xul/nsSliderFrame.cpp

@@ -932,7 +932,8 @@ nsSliderMediator::HandleEvent(dom::Event* aEvent)
   return NS_OK;
 }
 
-class AsyncScrollbarDragStarter : public nsAPostRefreshObserver {
+class AsyncScrollbarDragStarter final : public nsAPostRefreshObserver
+{
 public:
   AsyncScrollbarDragStarter(nsIPresShell* aPresShell,
                             nsIWidget* aWidget,

layout/xul/nsXULPopupManager.cpp

@@ -1067,7 +1067,7 @@ nsXULPopupManager::HidePopup(nsIContent* aPopup,
 }
 
 // This is used to hide the popup after a transition finishes.
-class TransitionEnder : public nsIDOMEventListener
+class TransitionEnder final : public nsIDOMEventListener
 {
 protected:
   virtual ~TransitionEnder() { }