remove (unused) GatherPixelRefs

src/utils/SkGatherPixelRefsAndRects.cpp

-/*
- * Copyright 2014 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#include "SkGatherPixelRefsAndRects.h"
-#include "SkNoSaveLayerCanvas.h"
-#include "SkPictureUtils.h"
-
-void SkPictureUtils::GatherPixelRefsAndRects(SkPicture* pict,
-                                             SkPictureUtils::SkPixelRefContainer* prCont) {
-    if (pict->cullRect().isEmpty()) {
-        return ;
-    }
-
-    SkGatherPixelRefsAndRectsDevice device(SkScalarCeilToInt(pict->cullRect().width()), 
-                                           SkScalarCeilToInt(pict->cullRect().height()), 
-                                           prCont);
-    SkNoSaveLayerCanvas canvas(&device);
-
-    canvas.clipRect(pict->cullRect(), SkRegion::kIntersect_Op, false);
-    canvas.drawPicture(pict);
-}