Switch AlphaThresholdFilter over to new onFilterImage interface

include/core/SkImageFilter.h

Index: include/core/SkImageFilter.h
diff --git a/include/core/SkImageFilter.h b/include/core/SkImageFilter.h
index 8a8e512254f2e42e8515fee9844b18898416f319..1c87b42969ed95f4a19842280ac9f357d0c00c6a 100644
--- a/include/core/SkImageFilter.h
+++ b/include/core/SkImageFilter.h
@@ -418,13 +418,12 @@ protected:
         return false;
     }
 
-    /** Given a "srcBounds" rect, computes destination bounds for this
-     *  destination bounds for this filter. "dstBounds" are computed by
-     *  transforming the crop rect by the context's CTM, applying it to the
-     *  initial bounds, and intersecting the result with the context's clip
-     *  bounds.  "srcBounds" (if non-null) are computed by intersecting the
-     *  initial bounds with "dstBounds", to ensure that we never sample
-     *  outside of the crop rect (this restriction may be relaxed in the
+    /** Given a "srcBounds" rect, computes destination bounds for this filter.
+     *  "dstBounds" are computed by transforming the crop rect by the context's
+     *  CTM, applying it to the initial bounds, and intersecting the result with
+     *  the context's clip bounds.  "srcBounds" (if non-null) are computed by 
+     *  intersecting the initial bounds with "dstBounds", to ensure that we never

[Stephen White, 2016/04/11 20:48:20]

Nit: extra indentation before "intersecting"

[robertphillips, 2016/04/12 15:36:38]

I think that's just a code review artifact. It lines up in the code.

[Stephen White, 2016/04/12 15:41:39]

You're right! Never mind.

+     *  sample outside of the crop rect (this restriction may be relaxed in the
      *  future).

[Stephen White, 2016/04/11 20:48:20]

(To here.)

[robertphillips, 2016/04/12 15:36:38]

Not sure what this means.

[Stephen White, 2016/04/12 15:41:39]

The end of the indentation weirdness above; ignore.

      */
     bool applyCropRect(const Context&, const SkIRect& srcBounds, SkIRect* dstBounds) const;