Move code to dump GrSurface as a png to helper files

src/gpu/GrSurfacePriv.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrSurfacePriv_DEFINED
 #define GrSurfacePriv_DEFINED
 
 #include "GrSurface.h"
+#include "SkImagesSupport.h"
 
 /** Class that adds methods to GrSurface that are only intended for use internal to Skia.
     This class is purely a privileged window into GrSurface. It should never have additional data
     members or virtual methods.
     Non-static methods that are not trivial inlines should be spring-boarded (e.g. declared and
     implemented privately in GrSurface with a inline public method here). */
 class GrSurfacePriv {
 public:
     /**
      * Derive a SkImageInfo from the surface's descriptor. This is lossy as ImageInfo has fields not
      * known to GrSurface (e.g. alphaType).
      */
     SkImageInfo info() const { return fSurface->info(); }
 
     /**
      * Checks whether this GrSurface refers to the same GPU object as other. This
      * catches the case where a GrTexture and GrRenderTarget refer to the same
      * GPU memory.
      */
     bool isSameAs(const GrSurface* other) const { return fSurface->isSameAs(other); }
 
-    /**
-     * Write the contents of the surface to a PNG. Returns true if successful.
-     * @param filename      Full path to desired file
-     */
-    bool savePixels(const char* filename) { return fSurface->savePixels(filename); }
-
     bool hasPendingRead() const { return fSurface->hasPendingRead(); }
     bool hasPendingWrite() const { return fSurface->hasPendingWrite(); }
     bool hasPendingIO() const { return fSurface->hasPendingIO(); }
 
 private:
     GrSurfacePriv(GrSurface* surface) : fSurface(surface) { }
     GrSurfacePriv(const GrSurfacePriv& that) : fSurface(that.fSurface) { }
     GrSurfacePriv& operator=(const GrSurface&); // unimpl
 
     // No taking addresses of this type.
     const GrSurfacePriv* operator&() const;
     GrSurfacePriv* operator&();
 
     GrSurface* fSurface;
 
     friend class GrSurface; // to construct/copy this type.
 };
 
 inline GrSurfacePriv GrSurface::surfacePriv() { return GrSurfacePriv(this); }
 
 inline const GrSurfacePriv GrSurface::surfacePriv() const {
     return GrSurfacePriv(const_cast<GrSurface*>(this));
 }
 
 #endif