diff --git a/gfx/layers/basic/BasicLayers.cpp b/gfx/layers/basic/BasicLayers.cpp
index b85cf519fadd..5b997ffce7c3 100644
--- a/gfx/layers/basic/BasicLayers.cpp
+++ b/gfx/layers/basic/BasicLayers.cpp
@@ -58,6 +58,7 @@
 #include "gfxUtils.h"
 #include "ThebesLayerBuffer.h"
 #include "nsIWidget.h"
+#include "ReadbackProcessor.h"
 
 #include "GLContext.h"
 
@@ -106,9 +107,16 @@ public:
    * set up to account for all the properties of the layer (transform,
    * opacity, etc).
    */
-  virtual void Paint(gfxContext* aContext,
-                     LayerManager::DrawThebesLayerCallback aCallback,
-                     void* aCallbackData) {}
+  virtual void Paint(gfxContext* aContext) {}
+
+  /**
+   * Like Paint() but called for ThebesLayers with the additional parameters
+   * they need.
+   */
+  virtual void PaintThebes(gfxContext* aContext,
+                           LayerManager::DrawThebesLayerCallback aCallback,
+                           void* aCallbackData,
+                           ReadbackProcessor* aReadback) {}
 
   virtual ShadowableLayer* AsShadowableLayer() { return nsnull; }
 
@@ -380,9 +388,10 @@ public:
     mValidRegion.Sub(mValidRegion, aRegion);
   }
 
-  virtual void Paint(gfxContext* aContext,
-                     LayerManager::DrawThebesLayerCallback aCallback,
-                     void* aCallbackData);
+  virtual void PaintThebes(gfxContext* aContext,
+                           LayerManager::DrawThebesLayerCallback aCallback,
+                           void* aCallbackData,
+                           ReadbackProcessor* aReadback);
 
   virtual void ClearCachedResources() { mBuffer.Clear(); mValidRegion.SetEmpty(); }
   
@@ -507,14 +516,20 @@ PushGroupForLayer(gfxContext* aContext, Layer* aLayer, const nsIntRegion& aRegio
 }
 
 void
-BasicThebesLayer::Paint(gfxContext* aContext,
-                        LayerManager::DrawThebesLayerCallback aCallback,
-                        void* aCallbackData)
+BasicThebesLayer::PaintThebes(gfxContext* aContext,
+                              LayerManager::DrawThebesLayerCallback aCallback,
+                              void* aCallbackData,
+                              ReadbackProcessor* aReadback)
 {
   NS_ASSERTION(BasicManager()->InDrawing(),
                "Can only draw in drawing phase");
   nsRefPtr<gfxASurface> targetSurface = aContext->CurrentSurface();
 
+  nsTArray<ReadbackProcessor::Update> readbackUpdates;
+  if (aReadback && UsedForReadback()) {
+    aReadback->GetThebesLayerUpdates(this, &readbackUpdates);
+  }
+
   PRBool canUseOpaqueSurface = CanUseOpaqueSurface();
   Buffer::ContentType contentType =
     canUseOpaqueSurface ? gfxASurface::CONTENT_COLOR :
@@ -525,6 +540,8 @@ BasicThebesLayer::Paint(gfxContext* aContext,
       (!canUseOpaqueSurface &&
        (mContentFlags & CONTENT_COMPONENT_ALPHA) &&
        !MustRetainContent())) {
+    NS_ASSERTION(readbackUpdates.IsEmpty(), "Can't do readback for non-retained layer");
+
     mValidRegion.SetEmpty();
     mBuffer.Clear();
 
@@ -587,6 +604,20 @@ BasicThebesLayer::Paint(gfxContext* aContext,
   }
 
   mBuffer.DrawTo(this, aContext, opacity);
+
+  for (PRUint32 i = 0; i < readbackUpdates.Length(); ++i) {
+    ReadbackProcessor::Update& update = readbackUpdates[i];
+    nsIntPoint offset = update.mLayer->GetBackgroundLayerOffset();
+    nsRefPtr<gfxContext> ctx =
+      update.mLayer->GetSink()->BeginUpdate(update.mUpdateRect + offset,
+                                            update.mSequenceCounter);
+    if (ctx) {
+      NS_ASSERTION(opacity == 1.0, "Should only read back opaque layers");
+      ctx->Translate(gfxPoint(offset.x, offset.y));
+      mBuffer.DrawTo(this, ctx, 1.0);
+      update.mLayer->GetSink()->EndUpdate(ctx, update.mUpdateRect + offset);
+    }
+  }
 }
 
 static PRBool
@@ -667,9 +698,7 @@ public:
     ImageLayer::SetVisibleRegion(aRegion);
   }
 
-  virtual void Paint(gfxContext* aContext,
-                     LayerManager::DrawThebesLayerCallback aCallback,
-                     void* aCallbackData);
+  virtual void Paint(gfxContext* aContext);
 
   static void PaintContext(gfxPattern* aPattern,
                            const nsIntRegion& aVisible,
@@ -691,9 +720,7 @@ protected:
 };
 
 void
-BasicImageLayer::Paint(gfxContext* aContext,
-                       LayerManager::DrawThebesLayerCallback aCallback,
-                       void* aCallbackData)
+BasicImageLayer::Paint(gfxContext* aContext)
 {
   nsRefPtr<gfxPattern> dontcare =
       GetAndPaintCurrentImage(aContext, GetEffectiveOpacity());
@@ -799,9 +826,7 @@ public:
     ColorLayer::SetVisibleRegion(aRegion);
   }
 
-  virtual void Paint(gfxContext* aContext,
-                     LayerManager::DrawThebesLayerCallback aCallback,
-                     void* aCallbackData)
+  virtual void Paint(gfxContext* aContext)
   {
     PaintColorTo(mColor, GetEffectiveOpacity(), aContext);
   }
@@ -847,9 +872,7 @@ public:
 
   virtual void Initialize(const Data& aData);
   virtual void Updated(const nsIntRect& aRect);
-  virtual void Paint(gfxContext* aContext,
-                     LayerManager::DrawThebesLayerCallback aCallback,
-                     void* aCallbackData);
+  virtual void Paint(gfxContext* aContext);
 
   virtual void PaintWithOpacity(gfxContext* aContext,
                                 float aOpacity);
@@ -959,9 +982,7 @@ BasicCanvasLayer::Updated(const nsIntRect& aRect)
 }
 
 void
-BasicCanvasLayer::Paint(gfxContext* aContext,
-                        LayerManager::DrawThebesLayerCallback aCallback,
-                        void* aCallbackData)
+BasicCanvasLayer::Paint(gfxContext* aContext)
 {
   PaintWithOpacity(aContext, GetEffectiveOpacity());
 }
@@ -998,6 +1019,34 @@ BasicCanvasLayer::PaintWithOpacity(gfxContext* aContext,
   mUpdatedRect.Empty();
 }
 
+class BasicReadbackLayer : public ReadbackLayer,
+                           BasicImplData
+{
+public:
+  BasicReadbackLayer(BasicLayerManager* aLayerManager) :
+    ReadbackLayer(aLayerManager, static_cast<BasicImplData*>(this))
+  {
+    MOZ_COUNT_CTOR(BasicReadbackLayer);
+  }
+  virtual ~BasicReadbackLayer()
+  {
+    MOZ_COUNT_DTOR(BasicReadbackLayer);
+  }
+
+  virtual void SetVisibleRegion(const nsIntRegion& aRegion)
+  {
+    NS_ASSERTION(BasicManager()->InConstruction(),
+                 "Can only set properties in construction phase");
+    ReadbackLayer::SetVisibleRegion(aRegion);
+  }
+
+protected:
+  BasicLayerManager* BasicManager()
+  {
+    return static_cast<BasicLayerManager*>(mManager);
+  }
+};
+
 static nsIntRect
 ToOutsideIntRect(const gfxRect &aRect)
 {
@@ -1298,7 +1347,7 @@ BasicLayerManager::EndTransactionInternal(DrawThebesLayerCallback aCallback,
     MarkLeafLayersCoveredByOpaque(mRoot,
                                   mRoot->GetEffectiveVisibleRegion().GetBounds(),
                                   region);
-    PaintLayer(mRoot, aCallback, aCallbackData);
+    PaintLayer(mRoot, aCallback, aCallbackData, nsnull);
 
     // If we're doing manual double-buffering, we need to avoid drawing
     // the results of an incomplete transaction to the destination surface.
@@ -1369,7 +1418,8 @@ BasicLayerManager::SetRoot(Layer* aLayer)
 void
 BasicLayerManager::PaintLayer(Layer* aLayer,
                               DrawThebesLayerCallback aCallback,
-                              void* aCallbackData)
+                              void* aCallbackData,
+                              ReadbackProcessor* aReadback)
 {
   const nsIntRect* clipRect = aLayer->GetEffectiveClipRect();
   const gfx3DMatrix& effectiveTransform = aLayer->GetEffectiveTransform();
@@ -1431,11 +1481,21 @@ BasicLayerManager::PaintLayer(Layer* aLayer,
                    (void*)aLayer, data->IsCoveredByOpaque()));
 #endif
     if (!data->IsCoveredByOpaque()) {
-      data->Paint(mTarget, aCallback, aCallbackData);
+      if (aLayer->AsThebesLayer()) {
+        data->PaintThebes(mTarget, aCallback, aCallbackData, aReadback);
+      } else {
+        data->Paint(mTarget);
+      }
     }
   } else {
+    ReadbackProcessor readback;
+    if (IsRetained()) {
+      ContainerLayer* container = static_cast<ContainerLayer*>(aLayer);
+      readback.BuildUpdates(container);
+    }
+
     for (; child; child = child->GetNextSibling()) {
-      PaintLayer(child, aCallback, aCallbackData);
+      PaintLayer(child, aCallback, aCallbackData, &readback);
       if (mTransactionIncomplete)
         break;
     }
@@ -1519,6 +1579,13 @@ BasicLayerManager::CreateCanvasLayer()
   return layer.forget();
 }
 
+already_AddRefed<ReadbackLayer>
+BasicLayerManager::CreateReadbackLayer()
+{
+  NS_ASSERTION(InConstruction(), "Only allowed in construction phase");
+  nsRefPtr<ReadbackLayer> layer = new BasicReadbackLayer(this);
+  return layer.forget();
+}
 
 #ifdef MOZ_IPC
 
@@ -1575,6 +1642,19 @@ ToShadowable(Layer* aLayer)
   return ToData(aLayer)->AsShadowableLayer();
 }
 
+// Some layers, like ReadbackLayers, can't be shadowed and shadowing
+// them doesn't make sense anyway
+static bool
+ShouldShadow(Layer* aLayer)
+{
+  if (!ToShadowable(aLayer)) {
+    NS_ABORT_IF_FALSE(aLayer->GetType() == Layer::TYPE_READBACK,
+                      "Only expect not to shadow ReadbackLayers");
+    return false;
+  }
+  return true;
+}
+
 template<class OpT>
 static BasicShadowableLayer*
 GetBasicShadowable(const OpT& op)
@@ -1622,7 +1702,10 @@ private:
 void
 BasicShadowableContainerLayer::InsertAfter(Layer* aChild, Layer* aAfter)
 {
-  if (HasShadow()) {
+  if (HasShadow() && ShouldShadow(aChild)) {
+    while (aAfter && !ShouldShadow(aAfter)) {
+      aAfter = aAfter->GetPrevSibling();
+    }
     ShadowManager()->InsertAfter(ShadowManager()->Hold(this),
                                  ShadowManager()->Hold(aChild),
                                  aAfter ? ShadowManager()->Hold(aAfter) : nsnull);
@@ -1633,7 +1716,7 @@ BasicShadowableContainerLayer::InsertAfter(Layer* aChild, Layer* aAfter)
 void
 BasicShadowableContainerLayer::RemoveChild(Layer* aChild)
 {
-  if (HasShadow()) {
+  if (HasShadow() && ShouldShadow(aChild)) {
     ShadowManager()->RemoveChild(ShadowManager()->Hold(this),
                                  ShadowManager()->Hold(aChild));
   }
@@ -1857,9 +1940,7 @@ public:
     MOZ_COUNT_DTOR(BasicShadowableImageLayer);
   }
 
-  virtual void Paint(gfxContext* aContext,
-                     LayerManager::DrawThebesLayerCallback aCallback,
-                     void* aCallbackData);
+  virtual void Paint(gfxContext* aContext);
 
   virtual void FillSpecificAttributes(SpecificLayerAttributes& aAttrs)
   {
@@ -1890,9 +1971,7 @@ private:
 };
  
 void
-BasicShadowableImageLayer::Paint(gfxContext* aContext,
-                                 LayerManager::DrawThebesLayerCallback aCallback,
-                                 void* aCallbackData)
+BasicShadowableImageLayer::Paint(gfxContext* aContext)
 {
   gfxIntSize oldSize = mSize;
   nsRefPtr<gfxPattern> pat = GetAndPaintCurrentImage(aContext, GetEffectiveOpacity());
@@ -1977,9 +2056,7 @@ public:
   }
 
   virtual void Initialize(const Data& aData);
-  virtual void Paint(gfxContext* aContext,
-                     LayerManager::DrawThebesLayerCallback aCallback,
-                     void* aCallbackData);
+  virtual void Paint(gfxContext* aContext);
 
   virtual void FillSpecificAttributes(SpecificLayerAttributes& aAttrs)
   {
@@ -2040,11 +2117,9 @@ BasicShadowableCanvasLayer::Initialize(const Data& aData)
 }
 
 void
-BasicShadowableCanvasLayer::Paint(gfxContext* aContext,
-                                  LayerManager::DrawThebesLayerCallback aCallback,
-                                  void* aCallbackData)
+BasicShadowableCanvasLayer::Paint(gfxContext* aContext)
 {
-  BasicCanvasLayer::Paint(aContext, aCallback, aCallbackData);
+  BasicCanvasLayer::Paint(aContext);
   if (!HasShadow())
     return;
 
@@ -2167,9 +2242,10 @@ public:
     }
   }
 
-  virtual void Paint(gfxContext* aContext,
-                     LayerManager::DrawThebesLayerCallback aCallback,
-                     void* aCallbackData);
+  virtual void PaintThebes(gfxContext* aContext,
+                           LayerManager::DrawThebesLayerCallback aCallback,
+                           void* aCallbackData,
+                           ReadbackProcessor* aReadback);
 
 private:
   BasicShadowLayerManager* BasicManager()
@@ -2261,9 +2337,10 @@ BasicShadowThebesLayer::Swap(const ThebesBuffer& aNewFront,
 }
 
 void
-BasicShadowThebesLayer::Paint(gfxContext* aContext,
-                              LayerManager::DrawThebesLayerCallback aCallback,
-                              void* aCallbackData)
+BasicShadowThebesLayer::PaintThebes(gfxContext* aContext,
+                                    LayerManager::DrawThebesLayerCallback aCallback,
+                                    void* aCallbackData,
+                                    ReadbackProcessor* aReadback)
 {
   NS_ASSERTION(BasicManager()->InDrawing(),
                "Can only draw in drawing phase");
@@ -2357,9 +2434,7 @@ public:
     mFrontSurface = nsnull;
   }
 
-  virtual void Paint(gfxContext* aContext,
-                     LayerManager::DrawThebesLayerCallback aCallback,
-                     void* aCallbackData);
+  virtual void Paint(gfxContext* aContext);
 
 protected:
   BasicShadowLayerManager* BasicManager()
@@ -2390,9 +2465,7 @@ BasicShadowImageLayer::Swap(gfxSharedImageSurface* newFront)
 }
 
 void
-BasicShadowImageLayer::Paint(gfxContext* aContext,
-                             LayerManager::DrawThebesLayerCallback aCallback,
-                             void* aCallbackData)
+BasicShadowImageLayer::Paint(gfxContext* aContext)
 {
   if (!mFrontSurface) {
     return;
@@ -2425,9 +2498,7 @@ public:
     MOZ_COUNT_DTOR(BasicShadowColorLayer);
   }
 
-  virtual void Paint(gfxContext* aContext,
-                     LayerManager::DrawThebesLayerCallback aCallback,
-                     void* aCallbackData)
+  virtual void Paint(gfxContext* aContext)
   {
     BasicColorLayer::PaintColorTo(mColor, GetEffectiveOpacity(), aContext);
   }
@@ -2469,9 +2540,7 @@ public:
     mFrontSurface = nsnull;
   }
 
-  virtual void Paint(gfxContext* aContext,
-                     LayerManager::DrawThebesLayerCallback aCallback,
-                     void* aCallbackData);
+  virtual void Paint(gfxContext* aContext);
 
 private:
   BasicShadowLayerManager* BasicManager()
@@ -2503,9 +2572,7 @@ BasicShadowCanvasLayer::Swap(gfxSharedImageSurface* newFront)
 }
 
 void
-BasicShadowCanvasLayer::Paint(gfxContext* aContext,
-                              LayerManager::DrawThebesLayerCallback aCallback,
-                              void* aCallbackData)
+BasicShadowCanvasLayer::Paint(gfxContext* aContext)
 {
   NS_ASSERTION(BasicManager()->InDrawing(),
                "Can only draw in drawing phase");
@@ -2676,7 +2743,7 @@ BasicShadowLayerManager::Mutated(Layer* aLayer)
   BasicLayerManager::Mutated(aLayer);
 
   NS_ASSERTION(InConstruction() || InDrawing(), "wrong phase");
-  if (HasShadowManager()) {
+  if (HasShadowManager() && ShouldShadow(aLayer)) {
     ShadowLayerForwarder::Mutated(Hold(aLayer));
   }
 }
diff --git a/gfx/layers/basic/BasicLayers.h b/gfx/layers/basic/BasicLayers.h
index a2f6f03594c3..6590f618001d 100644
--- a/gfx/layers/basic/BasicLayers.h
+++ b/gfx/layers/basic/BasicLayers.h
@@ -60,6 +60,7 @@ class ShadowContainerLayer;
 class ShadowImageLayer;
 class ShadowCanvasLayer;
 class ShadowColorLayer;
+class ReadbackProcessor;
 
 /**
  * This is a cairo/Thebes-only, main-thread-only implementation of layers.
@@ -152,16 +153,17 @@ public:
   virtual already_AddRefed<CanvasLayer> CreateCanvasLayer();
   virtual already_AddRefed<ImageContainer> CreateImageContainer();
   virtual already_AddRefed<ColorLayer> CreateColorLayer();
+  virtual already_AddRefed<ReadbackLayer> CreateReadbackLayer();
   virtual already_AddRefed<ShadowThebesLayer> CreateShadowThebesLayer()
-  { return NULL; }
+  { return nsnull; }
   virtual already_AddRefed<ShadowContainerLayer> CreateShadowContainerLayer()
-  { return NULL; }
+  { return nsnull; }
   virtual already_AddRefed<ShadowImageLayer> CreateShadowImageLayer()
-  { return NULL; }
+  { return nsnull; }
   virtual already_AddRefed<ShadowColorLayer> CreateShadowColorLayer()
-  { return NULL; }
+  { return nsnull; }
   virtual already_AddRefed<ShadowCanvasLayer> CreateShadowCanvasLayer()
-  { return NULL; }
+  { return nsnull; }
 
   virtual LayersBackend GetBackendType() { return LAYERS_BASIC; }
   virtual void GetBackendName(nsAString& name) { name.AssignLiteral("Basic"); }
@@ -197,7 +199,8 @@ protected:
   // Paints aLayer to mTarget.
   void PaintLayer(Layer* aLayer,
                   DrawThebesLayerCallback aCallback,
-                  void* aCallbackData);
+                  void* aCallbackData,
+                  ReadbackProcessor* aReadback);
 
   // Clear the contents of a layer
   void ClearLayer(Layer* aLayer);