new file mode 100644
--- /dev/null
+++ b/layout/base/GeometryUtils.cpp
@@ -0,0 +1,238 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "GeometryUtils.h"
+
+#include "mozilla/dom/GeometryUtilsBinding.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/Text.h"
+#include "mozilla/dom/DOMQuad.h"
+#include "nsIFrame.h"
+#include "nsGenericDOMDataNode.h"
+#include "nsCSSFrameConstructor.h"
+#include "nsLayoutUtils.h"
+#include "nsSVGUtils.h"
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+namespace mozilla {
+
+typedef OwningTextOrElementOrDocument GeometryNode;
+
+enum GeometryNodeType {
+  GEOMETRY_NODE_ELEMENT,
+  GEOMETRY_NODE_TEXT,
+  GEOMETRY_NODE_DOCUMENT
+};
+
+static nsIFrame*
+GetFrameForNode(nsINode* aNode, GeometryNodeType aType)
+{
+  nsIDocument* doc = aNode->OwnerDoc();
+  doc->FlushPendingNotifications(Flush_Layout);
+  switch (aType) {
+  case GEOMETRY_NODE_ELEMENT:
+    return aNode->AsContent()->GetPrimaryFrame();
+  case GEOMETRY_NODE_TEXT: {
+    nsIPresShell* presShell = doc->GetShell();
+    if (presShell) {
+      return presShell->FrameConstructor()->EnsureFrameForTextNode(
+          static_cast<nsGenericDOMDataNode*>(aNode));
+    }
+    return nullptr;
+  }
+  case GEOMETRY_NODE_DOCUMENT: {
+    nsIPresShell* presShell = doc->GetShell();
+    return presShell ? presShell->GetRootFrame() : nullptr;
+  }
+  default:
+    MOZ_ASSERT(false, "Unknown GeometryNodeType");
+    return nullptr;
+  }
+}
+
+static nsIFrame*
+GetFrameForGeometryNode(const Optional<GeometryNode>& aGeometryNode,
+                        nsINode* aDefaultNode)
+{
+  if (!aGeometryNode.WasPassed()) {
+    return GetFrameForNode(aDefaultNode->OwnerDoc(), GEOMETRY_NODE_DOCUMENT);
+  }
+
+  const GeometryNode& value = aGeometryNode.Value();
+  if (value.IsElement()) {
+    return GetFrameForNode(value.GetAsElement(), GEOMETRY_NODE_ELEMENT);
+  }
+  if (value.IsDocument()) {
+    return GetFrameForNode(value.GetAsDocument(), GEOMETRY_NODE_DOCUMENT);
+  }
+  return GetFrameForNode(value.GetAsText(), GEOMETRY_NODE_TEXT);
+}
+
+static nsIFrame*
+GetFrameForNode(nsINode* aNode)
+{
+  if (aNode->IsElement()) {
+    return GetFrameForNode(aNode, GEOMETRY_NODE_ELEMENT);
+  }
+  if (aNode == aNode->OwnerDoc()) {
+    return GetFrameForNode(aNode, GEOMETRY_NODE_DOCUMENT);
+  }
+  NS_ASSERTION(aNode->IsNodeOfType(nsINode::eTEXT), "Unknown node type");
+  return GetFrameForNode(aNode, GEOMETRY_NODE_TEXT);
+}
+
+static nsIFrame*
+GetFirstNonAnonymousFrameForGeometryNode(const Optional<GeometryNode>& aNode,
+                                         nsINode* aDefaultNode)
+{
+  nsIFrame* f = GetFrameForGeometryNode(aNode, aDefaultNode);
+  if (f) {
+    f = nsLayoutUtils::GetFirstNonAnonymousFrame(f);
+  }
+  return f;
+}
+
+/**
+ * This can modify aFrame to point to a different frame. This is needed to
+ * handle SVG, where SVG elements can only compute a rect that's valid with
+ * respect to the "outer SVG" frame.
+ */
+static nsRect
+GetBoxRectForFrame(nsIFrame** aFrame, CSSBoxType aType)
+{
+  nsRect r;
+  nsIFrame* f = nsSVGUtils::GetOuterSVGFrameAndCoveredRegion(*aFrame, &r);
+  if (f) {
+    // For SVG, the BoxType is ignored.
+    *aFrame = f;
+    return r;
+  }
+
+  f = *aFrame;
+  switch (aType) {
+  case CSSBoxType::Content: r = f->GetContentRectRelativeToSelf(); break;
+  case CSSBoxType::Padding: r = f->GetPaddingRectRelativeToSelf(); break;
+  case CSSBoxType::Border: r = nsRect(nsPoint(0, 0), f->GetSize()); break;
+  case CSSBoxType::Margin: {
+    r = nsRect(nsPoint(0, 0), f->GetSize());
+    r.Inflate(f->GetUsedMargin());
+    break;
+  }
+  default: MOZ_ASSERT(false, "unknown box type"); return r;
+  }
+
+  return r;
+}
+
+class AccumulateQuadCallback : public nsLayoutUtils::BoxCallback {
+public:
+  AccumulateQuadCallback(nsISupports* aParentObject,
+                         nsTArray<nsRefPtr<DOMQuad> >& aResult,
+                         nsIFrame* aRelativeToFrame,
+                         const nsPoint& aRelativeToBoxTopLeft,
+                         CSSBoxType aBoxType)
+    : mParentObject(aParentObject)
+    , mResult(aResult)
+    , mRelativeToFrame(aRelativeToFrame)
+    , mRelativeToBoxTopLeft(aRelativeToBoxTopLeft)
+    , mBoxType(aBoxType)
+  {
+  }
+
+  virtual void AddBox(nsIFrame* aFrame) MOZ_OVERRIDE
+  {
+    nsIFrame* f = aFrame;
+    nsRect box = GetBoxRectForFrame(&f, mBoxType);
+    nsPoint appUnits[4] =
+      { box.TopLeft(), box.TopRight(), box.BottomRight(), box.BottomLeft() };
+    CSSPoint points[4];
+    for (uint32_t i = 0; i < 4; ++i) {
+      points[i] = CSSPoint(nsPresContext::AppUnitsToFloatCSSPixels(appUnits[i].x),
+                           nsPresContext::AppUnitsToFloatCSSPixels(appUnits[i].y));
+    }
+    nsLayoutUtils::TransformResult rv =
+      nsLayoutUtils::TransformPoints(f, mRelativeToFrame, 4, points);
+    if (rv == nsLayoutUtils::TRANSFORM_SUCCEEDED) {
+      CSSPoint delta(nsPresContext::AppUnitsToFloatCSSPixels(mRelativeToBoxTopLeft.x),
+                     nsPresContext::AppUnitsToFloatCSSPixels(mRelativeToBoxTopLeft.y));
+      for (uint32_t i = 0; i < 4; ++i) {
+        points[i] -= delta;
+      }
+    } else {
+      PodArrayZero(points);
+    }
+    mResult.AppendElement(new DOMQuad(mParentObject, points));
+  }
+
+  nsISupports* mParentObject;
+  nsTArray<nsRefPtr<DOMQuad> >& mResult;
+  nsIFrame* mRelativeToFrame;
+  nsPoint mRelativeToBoxTopLeft;
+  CSSBoxType mBoxType;
+};
+
+static nsPresContext*
+FindTopLevelPresContext(nsPresContext* aPC)
+{
+  bool isChrome = aPC->IsChrome();
+  nsPresContext* pc = aPC;
+  for (;;) {
+    nsPresContext* parent = pc->GetParentPresContext();
+    if (!parent || parent->IsChrome() != isChrome) {
+      return pc;
+    }
+    pc = parent;
+  }
+}
+
+static bool
+CheckFramesInSameTopLevelBrowsingContext(nsIFrame* aFrame1, nsIFrame* aFrame2)
+{
+  nsPresContext* pc1 = aFrame1->PresContext();
+  nsPresContext* pc2 = aFrame2->PresContext();
+  if (pc1 == pc2) {
+    return true;
+  }
+  if (nsContentUtils::IsCallerChrome()) {
+    return true;
+  }
+  if (FindTopLevelPresContext(pc1) == FindTopLevelPresContext(pc2)) {
+    return true;
+  }
+  return false;
+}
+
+void GetBoxQuads(nsINode* aNode,
+                 const dom::BoxQuadOptions& aOptions,
+                 nsTArray<nsRefPtr<DOMQuad> >& aResult,
+                 ErrorResult& aRv)
+{
+  nsIFrame* frame = GetFrameForNode(aNode);
+  if (!frame) {
+    // No boxes to return
+    return;
+  }
+  nsIDocument* ownerDoc = aNode->OwnerDoc();
+  nsIFrame* relativeToFrame =
+    GetFirstNonAnonymousFrameForGeometryNode(aOptions.mRelativeTo, ownerDoc);
+  if (!relativeToFrame) {
+    aRv.Throw(NS_ERROR_DOM_NOT_FOUND_ERR);
+    return;
+  }
+  if (!CheckFramesInSameTopLevelBrowsingContext(frame, relativeToFrame)) {
+    aRv.Throw(NS_ERROR_DOM_NOT_FOUND_ERR);
+    return;
+  }
+  // GetBoxRectForFrame can modify relativeToFrame so call it first.
+  nsPoint relativeToTopLeft =
+      GetBoxRectForFrame(&relativeToFrame, CSSBoxType::Border).TopLeft();
+  AccumulateQuadCallback callback(ownerDoc, aResult, relativeToFrame,
+                                  relativeToTopLeft, aOptions.mBox);
+  nsLayoutUtils::GetAllInFlowBoxes(frame, &callback);
+}
+
+}

new file mode 100644
--- /dev/null
+++ b/layout/base/GeometryUtils.h
@@ -0,0 +1,41 @@
+/* -*- 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 MOZILLA_GEOMETRYUTILS_H_
+#define MOZILLA_GEOMETRYUTILS_H_
+
+#include "mozilla/ErrorResult.h"
+#include "nsTArray.h"
+#include "nsCOMPtr.h"
+
+/**
+ * This file defines utility functions for converting between layout
+ * coordinate systems.
+ */
+
+class nsINode;
+class nsIDocument;
+
+namespace mozilla {
+
+namespace dom {
+struct BoxQuadOptions;
+class DOMQuad;
+class Element;
+class Text;
+}
+
+/**
+ * Computes quads for aNode using aOptions, according to GeometryUtils.getBoxQuads.
+ * May set an error in aRv.
+ */
+void GetBoxQuads(nsINode* aNode,
+                 const dom::BoxQuadOptions& aOptions,
+                 nsTArray<nsRefPtr<dom::DOMQuad> >& aResult,
+                 ErrorResult& aRv);
+
+}
+
+#endif /* MOZILLA_GEOMETRYUTILS_H_ */

--- a/layout/base/moz.build
+++ b/layout/base/moz.build
@@ -55,25 +55,27 @@ EXPORTS += [
     'nsStyleChangeList.h',
     'ScrollbarStyles.h',
     'StackArena.h',
     'Units.h',
     'UnitTransforms.h',
 ]
 
 EXPORTS.mozilla += [
+    'GeometryUtils.h',
     'PaintTracker.h',
 ]
 
 UNIFIED_SOURCES += [
     'ActiveLayerTracker.cpp',
     'DisplayItemClip.cpp',
     'DisplayListClipState.cpp',
     'FrameLayerBuilder.cpp',
     'FramePropertyTable.cpp',
+    'GeometryUtils.cpp',
     'MaskLayerImageCache.cpp',
     'nsCaret.cpp',
     'nsCounterManager.cpp',
     'nsCSSColorUtils.cpp',
     'nsCSSFrameConstructor.cpp',
     'nsCSSRendering.cpp',
     'nsCSSRenderingBorders.cpp',
     'nsDisplayList.cpp',