add ImageGenerator::NewFromData to porting layer

tests/KtxTest.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 "Resources.h"
 #include "SkBitmap.h"
 #include "SkData.h"
-#include "SkDecodingImageGenerator.h"
+#include "SkImageGenerator.h"
 #include "SkForceLinking.h"
 #include "SkImageDecoder.h"
 #include "SkOSFile.h"
 #include "SkRandom.h"
 #include "SkStream.h"
 #include "Test.h"
 
 __SK_FORCE_IMAGE_DECODER_LINKING;
 
 /**
@@ skipping 122 matching lines @@
 
     // Load PKM file into a bitmap
     SkBitmap etcBitmap;
     SkAutoTUnref<SkData> fileData(SkData::NewFromFileName(pkmFilename.c_str()));
     if (NULL == fileData) {
         SkDebugf("KtxReexportPKM: can't load test file %s\n", pkmFilename.c_str());
         return;
     }
 
     bool installDiscardablePixelRefSuccess =
-        SkInstallDiscardablePixelRef(
-            SkDecodingImageGenerator::Create(
-                fileData, SkDecodingImageGenerator::Options()), &etcBitmap);
+        SkInstallDiscardablePixelRef(fileData, &etcBitmap);
     REPORTER_ASSERT(reporter, installDiscardablePixelRefSuccess);
 
     // Write the bitmap out to a KTX file.
     SkData *ktxDataPtr = SkImageEncoder::EncodeData(etcBitmap, SkImageEncoder::kKTX_Type, 0);
     SkAutoDataUnref newKtxData(ktxDataPtr);
     REPORTER_ASSERT(reporter, ktxDataPtr);
 
     // See is this data is identical to data in existing ktx file.
     SkString ktxFilename = GetResourcePath("mandrill_128.ktx");
     SkAutoDataUnref oldKtxData(SkData::NewFromFileName(ktxFilename.c_str()));
     REPORTER_ASSERT(reporter, oldKtxData->equals(newKtxData));
 }