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

include/core/SkCanvas.h

Index: include/core/SkCanvas.h
diff --git a/include/core/SkCanvas.h b/include/core/SkCanvas.h
index 53f6dda88b090c5734a7e7104925ae0749bb76d9..7ffe6699e5e7b4397b7ff7a919d2b0bc666d65d1 100644
--- a/include/core/SkCanvas.h
+++ b/include/core/SkCanvas.h
@@ -1428,6 +1428,13 @@ private:
      */
     bool wouldOverwriteEntireSurface(const SkRect*, const SkPaint*, ShaderOverrideOpacity) const;
 
+    /**
+     *  Returns true if the paint's imagefilter can be invoked directly, without needed a temp
+     *  layer. This method calls through to the corresponding method on Device, but it also
+     *  checks the clip, as currently the filter can only be invoked directly if the result will
+     *  be clipped to the bounds of the bitmap (or smaller).
+     */
+    bool canCallFilterSprite(const SkRect& bounds, const SkPaint&);
 
     /*  These maintain a cache of the clip bounds in local coordinates,
         (converted to 2s-compliment if floats are slow).