diff --git a/gfx/layers/Layers.cpp b/gfx/layers/Layers.cpp
index cb3fd8955e1..50fff935fa0 100644
--- a/gfx/layers/Layers.cpp
+++ b/gfx/layers/Layers.cpp
@@ -38,6 +38,10 @@
  *
  * ***** END LICENSE BLOCK ***** */
 
+#ifdef MOZ_IPC
+# include "mozilla/layers/ShadowLayers.h"
+#endif  // MOZ_IPC
+
 #include "ImageLayers.h"
 #include "Layers.h"
 #include "gfxPlatform.h"
@@ -200,8 +204,50 @@ Layer::CanUseOpaqueSurface()
     parent->CanUseOpaqueSurface();
 }
 
+
+#ifdef MOZ_IPC
+// NB: eventually these methods will be defined unconditionally, and
+// can be moved into Layers.h
+const nsIntRect*
+Layer::GetEffectiveClipRect()
+{
+  if (ShadowLayer* shadow = AsShadowLayer()) {
+    return shadow->GetShadowClipRect();
+  }
+  return GetClipRect();
+}
+
+const nsIntRegion&
+Layer::GetEffectiveVisibleRegion()
+{
+  if (ShadowLayer* shadow = AsShadowLayer()) {
+    return shadow->GetShadowVisibleRegion();
+  }
+  return GetVisibleRegion();
+}
+
+const gfx3DMatrix&
+Layer::GetEffectiveTransform()
+{
+  if (ShadowLayer* shadow = AsShadowLayer()) {
+    return shadow->GetShadowTransform();
+  }
+  return GetTransform();
+}
+
+#else
+
+const nsIntRect* Layer::GetEffectiveClipRect() { return GetClipRect(); }
+const nsIntRegion& Layer::GetEffectiveVisibleRegion() { return GetVisibleRegion(); }
+const gfx3DMatrix& Layer::GetEffectiveTransform() { return GetTransform(); }
+
+#endif  // MOZ_IPC
+
+
 #ifdef MOZ_LAYERS_HAVE_LOG
 
+static nsACString& PrintInfo(nsACString& aTo, ShadowLayer* aShadowLayer);
+
 void
 Layer::Dump(FILE* aFile, const char* aPrefix)
 {
@@ -260,6 +306,8 @@ Layer::PrintInfo(nsACString& aTo, const char* aPrefix)
   aTo += aPrefix;
   aTo += nsPrintfCString(64, "%s%s (0x%p)", mManager->Name(), Name(), this);
 
+  ::PrintInfo(aTo, AsShadowLayer());
+
   if (mUseClipRect) {
     AppendToString(aTo, mClipRect, " [clip=", "]");
   }
@@ -405,6 +453,28 @@ LayerManager::IsLogEnabled()
   return PR_LOG_TEST(sLog, PR_LOG_DEBUG);
 }
 
+# ifdef MOZ_IPC
+static nsACString&
+PrintInfo(nsACString& aTo, ShadowLayer* aShadowLayer)
+{
+  if (!aShadowLayer) {
+    return aTo;
+  }
+  if (const nsIntRect* clipRect = aShadowLayer->GetShadowClipRect()) {
+    AppendToString(aTo, *clipRect, " [shadow-clip=", "]");
+  }
+  if (!aShadowLayer->GetShadowTransform().IsIdentity()) {
+    AppendToString(aTo, aShadowLayer->GetShadowTransform(), " [shadow-transform=", "]");
+  }
+  if (!aShadowLayer->GetShadowVisibleRegion().IsEmpty()) {
+    AppendToString(aTo, aShadowLayer->GetShadowVisibleRegion(), " [shadow-visible=", "]");
+  }
+  return aTo;
+}
+# else
+static nsACString& PrintInfo(nsACString& aTo, ShadowLayer* aShadowLayer) {}
+# endif  // MOZ_IPC
+
 #else  // !MOZ_LAYERS_HAVE_LOG
 
 void Layer::Dump(FILE* aFile, const char* aPrefix) {}
diff --git a/gfx/layers/Layers.h b/gfx/layers/Layers.h
index 5b3e0ed3df4..9e522536e2c 100644
--- a/gfx/layers/Layers.h
+++ b/gfx/layers/Layers.h
@@ -77,6 +77,7 @@ class ImageLayer;
 class ColorLayer;
 class ImageContainer;
 class CanvasLayer;
+class ShadowLayer;
 class SpecificLayerAttributes;
 
 /**
@@ -643,6 +644,19 @@ public:
    */
   virtual ThebesLayer* AsThebesLayer() { return nsnull; }
 
+  /**
+   * Dynamic cast to a ShadowLayer.  Return null if this is not a
+   * ShadowLayer.  Can be used anytime.
+   */
+  virtual ShadowLayer* AsShadowLayer() { return nsnull; }
+
+  // These getters can be used anytime.  They return the effective
+  // values that should be used when drawing this layer to screen,
+  // accounting for this layer possibly being a shadow.
+  const nsIntRect* GetEffectiveClipRect();
+  const nsIntRegion& GetEffectiveVisibleRegion();
+  const gfx3DMatrix& GetEffectiveTransform();
+
   virtual const char* Name() const =0;
   virtual LayerType GetType() const =0;
 
diff --git a/gfx/layers/ipc/ShadowLayers.h b/gfx/layers/ipc/ShadowLayers.h
index 38aefd8533a..caf0907ed9e 100644
--- a/gfx/layers/ipc/ShadowLayers.h
+++ b/gfx/layers/ipc/ShadowLayers.h
@@ -385,18 +385,76 @@ protected:
 };
 
 
-class ShadowThebesLayer : public ThebesLayer
+/**
+ * A ShadowLayer is the representation of a child-context's Layer in a
+ * parent context.  They can be transformed, clipped,
+ * etc. independently of their origin Layers.
+ *
+ * Note that ShadowLayers can themselves have a shadow in a parent
+ * context.
+ */
+class ShadowLayer
 {
 public:
+  virtual ~ShadowLayer() {}
+
   /**
    * CONSTRUCTION PHASE ONLY
    */
-  void SetParent(PLayersParent* aParent)
+  void SetAllocator(PLayersParent* aAllocator)
   {
-    NS_ABORT_IF_FALSE(!mAllocator, "Stomping parent?");
-    mAllocator = aParent;
+    NS_ABORT_IF_FALSE(!mAllocator, "Stomping allocator?");
+    mAllocator = aAllocator;
   }
 
+  /**
+   * The following methods are
+   *
+   * CONSTRUCTION PHASE ONLY
+   *
+   * They are analogous to the Layer interface.
+   */
+  void SetShadowVisibleRegion(const nsIntRegion& aRegion)
+  {
+    mShadowVisibleRegion = aRegion;
+  }
+
+  void SetShadowClipRect(const nsIntRect* aRect)
+  {
+    mUseShadowClipRect = aRect != nsnull;
+    if (aRect) {
+      mShadowClipRect = *aRect;
+    }
+  }
+
+  void SetShadowTransform(const gfx3DMatrix& aMatrix)
+  {
+    mShadowTransform = aMatrix;
+  }
+
+  // These getters can be used anytime.
+  const nsIntRect* GetShadowClipRect() { return mUseShadowClipRect ? &mShadowClipRect : nsnull; }
+  const nsIntRegion& GetShadowVisibleRegion() { return mShadowVisibleRegion; }
+  const gfx3DMatrix& GetShadowTransform() { return mShadowTransform; }
+
+protected:
+  ShadowLayer()
+    : mAllocator(nsnull)
+    , mUseShadowClipRect(PR_FALSE)
+  {}
+
+  PLayersParent* mAllocator;
+  nsIntRegion mShadowVisibleRegion;
+  gfx3DMatrix mShadowTransform;
+  nsIntRect mShadowClipRect;
+  PRPackedBool mUseShadowClipRect;
+};
+
+
+class ShadowThebesLayer : public ShadowLayer,
+                          public ThebesLayer
+{
+public:
   /**
    * CONSTRUCTION PHASE ONLY
    *
@@ -450,30 +508,21 @@ public:
    */
   virtual void DestroyFrontBuffer() = 0;
 
+  virtual ShadowLayer* AsShadowLayer() { return this; }
+
   MOZ_LAYER_DECL_NAME("ShadowThebesLayer", TYPE_SHADOW)
 
 protected:
   ShadowThebesLayer(LayerManager* aManager, void* aImplData)
     : ThebesLayer(aManager, aImplData)
-    , mAllocator(nsnull)
   {}
-
-  PLayersParent* mAllocator;
 };
 
 
-class ShadowCanvasLayer : public CanvasLayer
+class ShadowCanvasLayer : public ShadowLayer,
+                          public CanvasLayer
 {
 public:
-  /**
-   * CONSTRUCTION PHASE ONLY
-   */
-  void SetParent(PLayersParent* aParent)
-  {
-    NS_ABORT_IF_FALSE(!mAllocator, "Stomping parent?");
-    mAllocator = aParent;
-  }
-
   /**
    * CONSTRUCTION PHASE ONLY
    *
@@ -491,30 +540,21 @@ public:
    */
   virtual void DestroyFrontBuffer() = 0;
 
+  virtual ShadowLayer* AsShadowLayer() { return this; }
+
   MOZ_LAYER_DECL_NAME("ShadowCanvasLayer", TYPE_SHADOW)
 
 protected:
   ShadowCanvasLayer(LayerManager* aManager, void* aImplData)
     : CanvasLayer(aManager, aImplData)
-    , mAllocator(nsnull)
   {}
-
-  PLayersParent* mAllocator;
 };
 
 
-class ShadowImageLayer : public ImageLayer
+class ShadowImageLayer : public ShadowLayer,
+                         public ImageLayer
 {
 public:
-  /**
-   * CONSTRUCTION PHASE ONLY
-   */
-  void SetParent(PLayersParent* aParent)
-  {
-    NS_ABORT_IF_FALSE(!mAllocator, "Stomping parent?");
-    mAllocator = aParent;
-  }
-
   /**
    * CONSTRUCTION PHASE ONLY
    *
@@ -539,15 +579,14 @@ public:
    */
   virtual void DestroyFrontBuffer() = 0;
 
+  virtual ShadowLayer* AsShadowLayer() { return this; }
+
   MOZ_LAYER_DECL_NAME("ShadowImageLayer", TYPE_SHADOW)
 
 protected:
   ShadowImageLayer(LayerManager* aManager, void* aImplData)
     : ImageLayer(aManager, aImplData)
-    , mAllocator(nsnull)
   {}
-
-  PLayersParent* mAllocator;
 };
 
 
diff --git a/gfx/layers/ipc/ShadowLayersParent.cpp b/gfx/layers/ipc/ShadowLayersParent.cpp
index 6917ebf90c4..3840e1f1d6f 100644
--- a/gfx/layers/ipc/ShadowLayersParent.cpp
+++ b/gfx/layers/ipc/ShadowLayersParent.cpp
@@ -152,7 +152,7 @@ ShadowLayersParent::RecvUpdate(const nsTArray<Edit>& cset,
 
       nsRefPtr<ShadowThebesLayer> layer =
         layer_manager()->CreateShadowThebesLayer();
-      layer->SetParent(this);
+      layer->SetAllocator(this);
       AsShadowLayer(edit.get_OpCreateThebesLayer())->Bind(layer);
       break;
     }
@@ -168,7 +168,7 @@ ShadowLayersParent::RecvUpdate(const nsTArray<Edit>& cset,
 
       nsRefPtr<ShadowImageLayer> layer =
         layer_manager()->CreateShadowImageLayer();
-      layer->SetParent(this);
+      layer->SetAllocator(this);
       AsShadowLayer(edit.get_OpCreateImageLayer())->Bind(layer);
       break;
     }
@@ -184,7 +184,7 @@ ShadowLayersParent::RecvUpdate(const nsTArray<Edit>& cset,
 
       nsRefPtr<ShadowCanvasLayer> layer = 
         layer_manager()->CreateShadowCanvasLayer();
-      layer->SetParent(this);
+      layer->SetAllocator(this);
       AsShadowLayer(edit.get_OpCreateCanvasLayer())->Bind(layer);
       break;
     }