Move code to dump GrSurface as a png to helper files

src/gpu/GrLayerCache.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 "GrAtlas.h"
 #include "GrGpu.h"
 #include "GrLayerCache.h"
@@ skipping 425 matching lines @@
 }
 
 #ifdef SK_DEVELOPER
 void GrLayerCache::writeLayersToDisk(const SkString& dirName) {
 
     GrTexture* atlasTexture = fAtlas->getTexture();
     if (NULL != atlasTexture) {
         SkString fileName(dirName);
         fileName.append("\\atlas.png");
 
-        atlasTexture->surfacePriv().savePixels(fileName.c_str());
+        SkSaveGrSurfacePixelsAsPNG(atlasTexture, fileName.c_str());
     }
 
     SkTDynamicHash<GrCachedLayer, GrCachedLayer::Key>::Iter iter(&fLayerHash);
     for (; !iter.done(); ++iter) {
         GrCachedLayer* layer = &(*iter);
 
         if (layer->isAtlased() || !layer->texture()) {
             continue;
         }
 
         SkString fileName(dirName);
         fileName.append("\\");
         fileName.appendU32(layer->fKey.pictureID());
         fileName.append("-");
         fileName.appendU32(layer->fKey.start());
         fileName.append(".png");
 
-        layer->texture()->surfacePriv().savePixels(fileName.c_str());
+        SkSaveGrSurfacePixelsAsPNG(layer->texture(), fileName.c_str());
     }
 }
 #endif