detect when we can filter bitmaps/images directly, w/o a tmp layer

include/core/SkDevice.h

Index: include/core/SkDevice.h
diff --git a/include/core/SkDevice.h b/include/core/SkDevice.h
index c52c579424a2ad7e450b501585052d0aa8eea050..a7a3895db4fe81936735fed1d41e825fc0a4612c 100644
--- a/include/core/SkDevice.h
+++ b/include/core/SkDevice.h
@@ -374,9 +374,13 @@ private:
     friend class SkDeviceFilteredPaint;
     friend class SkImageFilter::DeviceProxy;
     friend class SkNoPixelsBitmapDevice;
-
     friend class SkSurface_Raster;
 
+    /**
+     *  Calls through to drawSprite, processing imagefilter as needed.
+     */
+    void drawBitmapAsSprite(const SkDraw&, const SkBitmap&, int x, int y, const SkPaint&);
+
     // used to change the backend's pixels (and possibly config/rowbytes)
     // but cannot change the width/height, so there should be no change to
     // any clip information.