add ImageGenerator::NewFromData to porting layer

include/core/SkImageGenerator.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImageGenerator_DEFINED
 #define SkImageGenerator_DEFINED
 
@@ skipping 17 matching lines @@
  *  SkDELETE() on the generator.  Therefore, generator should be
  *  allocated with SkNEW() or SkNEW_ARGS().
  *
  *  @param destination Upon success, this bitmap will be
  *  configured and have a pixelref installed.
  *
  *  @return true iff successful.
  */
 SK_API bool SkInstallDiscardablePixelRef(SkImageGenerator*, SkBitmap* destination);
 
+/**
+ *  On success, installs a discradable pixelref into destination, based on encoded data.

[scroggo, 2015/01/07 21:47:45]

discardable*

+ *  Regardless of success or failure, the caller must still balance their ownership of encoded.
+ */
+SK_API bool SkInstallDiscardablePixelRef(SkData* encoded, SkBitmap* destination);
 
 /**
  *  An interface that allows a purgeable PixelRef (such as a
  *  SkDiscardablePixelRef) to decode and re-decode an image as needed.
  */
 class SK_API SkImageGenerator {
 public:
     /**
      *  The PixelRef which takes ownership of this SkImageGenerator
      *  will call the image generator's destructor.
@@ skipping 80 matching lines @@
     virtual bool onGetInfo(SkImageInfo* info);
     virtual bool onGetPixels(const SkImageInfo& info,
                              void* pixels, size_t rowBytes,
                              SkPMColor ctable[], int* ctableCount);
     virtual bool onGetYUV8Planes(SkISize sizes[3], void* planes[3], size_t rowBytes[3]);
     virtual bool onGetYUV8Planes(SkISize sizes[3], void* planes[3], size_t rowBytes[3],
                                  SkYUVColorSpace* colorSpace);
 };
 
 #endif  // SkImageGenerator_DEFINED