diff --git a/core/SkImageFilter.h b/core/SkImageFilter.h
index 6cc53c0..d89befa 100644
--- a/core/SkImageFilter.h
+++ b/core/SkImageFilter.h
@@ -99,16 +99,18 @@
      *  Returns true if the filter can be processed on the GPU.  This is most
      *  often used for multi-pass effects, where intermediate results must be
      *  rendered to textures.  For single-pass effects, use asNewEffect().
-     *  The default implementation returns false.
+     *  The default implementation returns asNewEffect(NULL, NULL).
      */
     virtual bool canFilterImageGPU() const;
 
     /**
-     *  Process this image filter on the GPU.  src is the source image for
-     *  processing, as a texture-backed bitmap.  result is the destination
-     *  bitmap, which should contain a texture-backed pixelref on success.
-     *  The default implementation returns returns false and ignores the
-     *  result parameter.
+     *  Process this image filter on the GPU.  This is most often used for 
+     *  multi-pass effects, where intermediate results must be rendered to
+     *  textures.  For single-pass effects, use asNewEffect().  src is the
+     *  source image for processing, as a texture-backed bitmap.  result is
+     *  the destination bitmap, which should contain a texture-backed pixelref
+     *  on success.  The default implementation does single-pass processing
+     *  using asNewEffect().
      */
     virtual bool filterImageGPU(Proxy*, const SkBitmap& src, SkBitmap* result);
 
diff --git a/core/SkImageFilterUtils.h b/core/SkImageFilterUtils.h
new file mode 100644
index 0000000..72a25fe
--- /dev/null
+++ b/core/SkImageFilterUtils.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2013 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkImageFilterUtils_DEFINED
+#define SkImageFilterUtils_DEFINED
+
+#if SK_SUPPORT_GPU
+
+#include "SkImageFilter.h"
+
+class SkBitmap;
+class GrTexture;
+class SkImageFilter;
+
+class SK_API SkImageFilterUtils {
+public:
+    /**
+     * Wrap the given texture in a texture-backed SkBitmap.
+     */
+    static bool WrapTexture(GrTexture* texture, int width, int height, SkBitmap* result);
+
+    /**
+     * Recursively evaluate the given filter on the GPU.  If filter is NULL,
+     * this function returns src.  If the filter has no GPU implementation, it
+     * will be processed in software and uploaded to the GPU.
+     */
+    static bool GetInputResultGPU(SkImageFilter* filter, SkImageFilter::Proxy* proxy, const SkBitmap& src, SkBitmap* result);
+};
+
+#endif
+
+#endif
diff --git a/effects/SkMagnifierImageFilter.h b/effects/SkMagnifierImageFilter.h
index e013426..80e3af6 100644
--- a/effects/SkMagnifierImageFilter.h
+++ b/effects/SkMagnifierImageFilter.h
@@ -16,7 +16,9 @@
 public:
     SkMagnifierImageFilter(SkRect srcRect, SkScalar inset);
 
+#if SK_SUPPORT_GPU
     virtual bool asNewEffect(GrEffectRef** effect, GrTexture* texture) const SK_OVERRIDE;
+#endif
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkMagnifierImageFilter)
 
diff --git a/effects/SkMatrixConvolutionImageFilter.h b/effects/SkMatrixConvolutionImageFilter.h
index cd2a16f..78a66f8 100644
--- a/effects/SkMatrixConvolutionImageFilter.h
+++ b/effects/SkMatrixConvolutionImageFilter.h
@@ -62,7 +62,7 @@
                                SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;
 
 #if SK_SUPPORT_GPU
-    virtual bool asNewEffect(GrEffectRef**, GrTexture*) const SK_OVERRIDE;
+    virtual bool asNewEffect(GrEffectRef** effect, GrTexture*) const SK_OVERRIDE;
 #endif
 
 private: