--- a/layout/base/RestyleManager.cpp
+++ b/layout/base/RestyleManager.cpp
@@ -8,16 +8,17 @@
  * changes need to happen, scheduling them, and doing them.
  */
 
 #include "mozilla/RestyleManager.h"
 
 #include <algorithm> // For std::max
 #include "mozilla/EffectSet.h"
 #include "mozilla/EventStates.h"
+#include "mozilla/ViewportFrame.h"
 #include "nsLayoutUtils.h"
 #include "AnimationCommon.h" // For GetLayerAnimationInfo
 #include "FrameLayerBuilder.h"
 #include "GeckoProfiler.h"
 #include "LayerAnimationInfo.h" // For LayerAnimationInfo::sRecords
 #include "nsAutoPtr.h"
 #include "nsStyleChangeList.h"
 #include "nsRuleProcessorData.h"
@@ -31,17 +32,16 @@
 #include "nsTransitionManager.h"
 #include "nsViewManager.h"
 #include "nsRenderingContext.h"
 #include "nsSVGIntegrationUtils.h"
 #include "nsCSSAnonBoxes.h"
 #include "nsContainerFrame.h"
 #include "nsPlaceholderFrame.h"
 #include "nsBlockFrame.h"
-#include "nsViewportFrame.h"
 #include "SVGTextFrame.h"
 #include "StickyScrollContainer.h"
 #include "nsIRootBox.h"
 #include "nsIDOMMutationEvent.h"
 #include "nsContentUtils.h"
 #include "nsIFrameInlines.h"
 #include "ActiveLayerTracker.h"
 #include "nsDisplayList.h"

rename from layout/generic/nsViewportFrame.cpp
rename to layout/generic/ViewportFrame.cpp
--- a/layout/generic/nsViewportFrame.cpp
+++ b/layout/generic/ViewportFrame.cpp
@@ -3,17 +3,18 @@
  * 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/. */
 
 /*
  * rendering object that is the root of the frame tree, which contains
  * the document's scrollbars and contains fixed-positioned elements
  */
 
-#include "nsViewportFrame.h"
+#include "mozilla/ViewportFrame.h"
+
 #include "nsGkAtoms.h"
 #include "nsIScrollableFrame.h"
 #include "nsSubDocumentFrame.h"
 #include "nsCanvasFrame.h"
 #include "nsAbsoluteContainingBlock.h"
 #include "GeckoProfiler.h"
 #include "nsIMozBrowserFrame.h"
 

rename from layout/generic/nsViewportFrame.h
rename to layout/generic/ViewportFrame.h
--- a/layout/generic/nsViewportFrame.h
+++ b/layout/generic/ViewportFrame.h
@@ -3,18 +3,18 @@
  * 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/. */
 
 /*
  * rendering object that is the root of the frame tree, which contains
  * the document's scrollbars and contains fixed-positioned elements
  */
 
-#ifndef nsViewportFrame_h___
-#define nsViewportFrame_h___
+#ifndef mozilla_ViewportFrame_h
+#define mozilla_ViewportFrame_h
 
 #include "mozilla/Attributes.h"
 #include "nsContainerFrame.h"
 
 class nsPresContext;
 
 namespace mozilla {
 
@@ -103,9 +103,9 @@ protected:
    * available width for aReflowInput accordingly.
    * @return the current scroll position, or 0,0 if not scrollable
    */
   nsPoint AdjustReflowInputForScrollbars(ReflowInput* aReflowInput) const;
 };
 
 } // namespace mozilla
 
-#endif // nsViewportFrame_h___
+#endif // mozilla_ViewportFrame_h

--- a/layout/generic/moz.build
+++ b/layout/generic/moz.build
@@ -107,16 +107,17 @@ EXPORTS += [
     'ScrollSnap.h',
     'Visibility.h',
 ]
 
 EXPORTS.mozilla += [
     'CSSAlignUtils.h',
     'ReflowInput.h',
     'ReflowOutput.h',
+    'ViewportFrame.h',
     'WritingModes.h',
 ]
 
 EXPORTS.mozilla.dom += [
     'Selection.h',
 ]
 
 EXPORTS.mozilla.layout += [
@@ -169,25 +170,25 @@ UNIFIED_SOURCES += [
     'nsSelection.cpp',
     'nsSimplePageSequenceFrame.cpp',
     'nsSplittableFrame.cpp',
     'nsSubDocumentFrame.cpp',
     'nsTextFrame.cpp',
     'nsTextFrameUtils.cpp',
     'nsTextRunTransformations.cpp',
     'nsVideoFrame.cpp',
-    'nsViewportFrame.cpp',
     'ReflowInput.cpp',
     'ReflowOutput.cpp',
     'RubyUtils.cpp',
     'ScrollbarActivity.cpp',
     'ScrollSnap.cpp',
     'ScrollVelocityQueue.cpp',
     'StickyScrollContainer.cpp',
     'TextOverflow.cpp',
+    'ViewportFrame.cpp',
 ]
 
 # nsLineLayout.cpp needs to be built separately because it uses plarena.h.
 # nsPluginFrame.cpp needs to be built separately because of name clashes in the OS X headers.
 SOURCES += [
     'nsLineLayout.cpp',
     'nsPluginFrame.cpp',
 ]

--- a/layout/generic/nsBRFrame.cpp
+++ b/layout/generic/nsBRFrame.cpp
@@ -1,16 +1,17 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 /* rendering object for HTML <br> elements */
 
 #include "nsCOMPtr.h"
+#include "nsContainerFrame.h"
 #include "nsFontMetrics.h"
 #include "nsFrame.h"
 #include "nsPresContext.h"
 #include "nsLineLayout.h"
 #include "nsStyleConsts.h"
 #include "nsGkAtoms.h"
 #include "nsRenderingContext.h"
 #include "nsLayoutUtils.h"

--- a/layout/generic/nsPageContentFrame.h
+++ b/layout/generic/nsPageContentFrame.h
@@ -1,17 +1,18 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #ifndef nsPageContentFrame_h___
 #define nsPageContentFrame_h___
 
 #include "mozilla/Attributes.h"
-#include "nsViewportFrame.h"
+#include "mozilla/ViewportFrame.h"
+
 class nsPageFrame;
 class nsSharedPageData;
 
 // Page frame class used by the simple page sequence frame
 class nsPageContentFrame : public mozilla::ViewportFrame {
 
 public:
   NS_DECL_FRAMEARENA_HELPERS

--- a/layout/ipc/RenderFrameParent.cpp
+++ b/layout/ipc/RenderFrameParent.cpp
@@ -9,32 +9,32 @@
 
 #include "BasicLayers.h"
 #include "gfxPrefs.h"
 #ifdef MOZ_ENABLE_D3D9_LAYER
 # include "LayerManagerD3D9.h"
 #endif //MOZ_ENABLE_D3D9_LAYER
 #include "mozilla/BrowserElementParent.h"
 #include "mozilla/EventForwards.h"  // for Modifiers
+#include "mozilla/ViewportFrame.h"
 #include "mozilla/dom/ContentChild.h"
 #include "mozilla/dom/ContentParent.h"
 #include "mozilla/dom/TabChild.h"
 #include "mozilla/dom/TabParent.h"
 #include "mozilla/layers/APZCTreeManager.h"
 #include "mozilla/layers/APZThreadUtils.h"
 #include "mozilla/layers/CompositorBridgeParent.h"
 #include "mozilla/layers/LayerTransactionParent.h"
 #include "nsContentUtils.h"
 #include "nsFocusManager.h"
 #include "nsFrameLoader.h"
 #include "nsIObserver.h"
 #include "nsStyleStructInlines.h"
 #include "nsSubDocumentFrame.h"
 #include "nsView.h"
-#include "nsViewportFrame.h"
 #include "RenderFrameParent.h"
 #include "mozilla/gfx/GPUProcessManager.h"
 #include "mozilla/layers/LayerManagerComposite.h"
 #include "mozilla/layers/CompositorBridgeChild.h"
 #include "ClientLayerManager.h"
 #include "FrameLayerBuilder.h"
 
 using namespace mozilla::dom;

--- a/layout/painting/nsDisplayList.cpp
+++ b/layout/painting/nsDisplayList.cpp
@@ -37,17 +37,16 @@
 #include "nsIFrameInlines.h"
 #include "nsThemeConstants.h"
 #include "BorderConsts.h"
 #include "LayerTreeInvalidation.h"
 
 #include "imgIContainer.h"
 #include "BasicLayers.h"
 #include "nsBoxFrame.h"
-#include "nsViewportFrame.h"
 #include "nsSubDocumentFrame.h"
 #include "nsSVGEffects.h"
 #include "nsSVGElement.h"
 #include "nsSVGClipPathFrame.h"
 #include "GeckoProfiler.h"
 #include "nsViewManager.h"
 #include "ImageLayers.h"
 #include "ImageContainer.h"
@@ -60,16 +59,17 @@
 #include "mozilla/EventStates.h"
 #include "mozilla/LookAndFeel.h"
 #include "mozilla/OperatorNewExtensions.h"
 #include "mozilla/PendingAnimationTracker.h"
 #include "mozilla/Preferences.h"
 #include "mozilla/Telemetry.h"
 #include "mozilla/UniquePtr.h"
 #include "mozilla/Unused.h"
+#include "mozilla/ViewportFrame.h"
 #include "mozilla/gfx/gfxVars.h"
 #include "ActiveLayerTracker.h"
 #include "nsContentUtils.h"
 #include "nsPrintfCString.h"
 #include "UnitTransforms.h"
 #include "LayersLogging.h"
 #include "FrameLayerBuilder.h"
 #include "mozilla/EventStateManager.h"