add ImageGenerator::NewFromData to porting layer

tests/ImageDecodingTest.cpp

 /*
  * Copyright 2013 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 "SkCanvas.h"
@@ skipping 437 matching lines @@
         0x68, 0xb6, 0x6d, 0xdb, 0x36, 0x22, 0xfa, 0x1f, 0x35, 0x75, 0x22, 0xec,
         0x31, 0xbc, 0x5d, 0x8f, 0x87, 0x53, 0xa2, 0x05, 0x8c, 0x2f, 0xcd, 0xa8,
         0xa7, 0xf3, 0xa3, 0xbd, 0x83, 0x8b, 0x2a, 0xc8, 0x58, 0xf5, 0xac, 0x80,
         0xe3, 0xfe, 0x66, 0xa4, 0x7c, 0x1b, 0x6c, 0xd1, 0xa9, 0xd8, 0x14, 0xd0,
         0xc5, 0xb5, 0x39, 0x71, 0x97, 0x19, 0x19, 0x1b
     };
     SkAutoDataUnref encoded(SkData::NewWithCopy(encodedWebP,
                                                 sizeof(encodedWebP)));
     SkBitmap bm;
 
-    bool success = SkInstallDiscardablePixelRef(
-        SkDecodingImageGenerator::Create(encoded,
-            SkDecodingImageGenerator::Options()), &bm);
+    bool success = SkInstallDiscardablePixelRef(encoded, &bm);
 
     REPORTER_ASSERT(reporter, success);
     if (!success) {
         return;
     }
     SkAutoLockPixels alp(bm);
 
     bool rightSize = ((kExpectedWidth == bm.width())
                       && (kExpectedHeight == bm.height()));
     REPORTER_ASSERT(reporter, rightSize);
@@ skipping 339 matching lines @@
                        ((void*)pixels.get(), sizeof(uint16_t) * pixelCount)));
     decoder->setAllocator(allocator);
     decoder->setSampleSize(2);
     SkBitmap bitmap;
     bool success = decoder->decode(stream, &bitmap, kRGB_565_SkColorType,
                                    SkImageDecoder::kDecodePixels_Mode) != SkImageDecoder::kFailure;
     REPORTER_ASSERT(r, success);
     REPORTER_ASSERT(r, !allocator->ready());  // Decoder used correct memory
     REPORTER_ASSERT(r, sentinal == pixels[pixelCount]);
 }