--- a/gfx/2d/2D.h
+++ b/gfx/2d/2D.h
@@ -934,16 +934,45 @@ public:
   virtual void PushClipRect(const Rect &aRect) = 0;
 
   /** Pop a clip from the DrawTarget. A pop without a corresponding push will
    * be ignored.
    */
   virtual void PopClip() = 0;
 
   /**
+   * Push a 'layer' to the DrawTarget, a layer is a temporary surface that all
+   * drawing will be redirected to, this is used for example to support group
+   * opacity or the masking of groups. Clips must be balanced within a layer,
+   * i.e. between a matching PushLayer/PopLayer pair there must be as many
+   * PushClip(Rect) calls as there are PopClip calls.
+   *
+   * @param aOpaque Whether the layer will be opaque
+   * @param aOpacity Opacity of the layer
+   * @param aMask Mask applied to the layer
+   * @param aMaskTransform Transform applied to the layer mask
+   * @param aBounds Optional bounds in device space to which the layer is
+   *                limited in size.
+   * @param aCopyBackground Whether to copy the background into the layer, this
+   *                        is only supported when aOpaque is true.
+   */
+  virtual void PushLayer(bool aOpaque, Float aOpacity,
+                         SourceSurface* aMask,
+                         const Matrix& aMaskTransform,
+                         const IntRect& aBounds = IntRect(),
+                         bool aCopyBackground = false) { MOZ_CRASH(); }
+
+  /**
+   * This balances a call to PushLayer and proceeds to blend the layer back
+   * onto the background. This blend will blend the temporary surface back
+   * onto the target in device space using POINT sampling and operator over.
+   */
+  virtual void PopLayer() { MOZ_CRASH(); }
+
+  /**
    * Create a SourceSurface optimized for use with this DrawTarget from
    * existing bitmap data in memory.
    *
    * The SourceSurface does not take ownership of aData, and may be freed at any time.
    */
   virtual already_AddRefed<SourceSurface> CreateSourceSurfaceFromData(unsigned char *aData,
                                                                   const IntSize &aSize,
                                                                   int32_t aStride,
@@ -1079,16 +1108,20 @@ public:
   void SetOpaqueRect(const IntRect &aRect) {
     mOpaqueRect = aRect;
   }
 
   const IntRect &GetOpaqueRect() const {
     return mOpaqueRect;
   }
 
+  virtual bool IsCurrentGroupOpaque() {
+    return GetFormat() == SurfaceFormat::B8G8R8X8;
+  }
+
   virtual void SetPermitSubpixelAA(bool aPermitSubpixelAA) {
     mPermitSubpixelAA = aPermitSubpixelAA;
   }
 
   bool GetPermitSubpixelAA() {
     return mPermitSubpixelAA;
   }