Revert of change all factories to return their base-class

tests/SerializationTest.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 "SkCanvas.h"
 #include "SkFixed.h"
@@ skipping 228 matching lines @@
 
 static void TestBitmapSerialization(const SkBitmap& validBitmap,
                                     const SkBitmap& invalidBitmap,
                                     bool shouldSucceed,
                                     skiatest::Reporter* reporter) {
     SkAutoTUnref<SkImage> validImage(SkImage::NewFromBitmap(validBitmap));
     SkAutoTUnref<SkImageFilter> validBitmapSource(SkImageSource::Create(validImage));
     SkAutoTUnref<SkImage> invalidImage(SkImage::NewFromBitmap(invalidBitmap));
     SkAutoTUnref<SkImageFilter> invalidBitmapSource(SkImageSource::Create(invalidImage));
     SkAutoTUnref<SkXfermode> mode(SkXfermode::Create(SkXfermode::kSrcOver_Mode));
-    SkAutoTUnref<SkImageFilter> xfermodeImageFilter(
+    SkAutoTUnref<SkXfermodeImageFilter> xfermodeImageFilter(
         SkXfermodeImageFilter::Create(mode, invalidBitmapSource, validBitmapSource));
 
     SkAutoTUnref<SkImageFilter> deserializedFilter(
         TestFlattenableSerialization<SkImageFilter>(
             xfermodeImageFilter, shouldSucceed, reporter));
 
     // Try to render a small bitmap using the invalid deserialized filter
     // to make sure we don't crash while trying to render it
     if (shouldSucceed) {
         SkBitmap bitmap;
@@ skipping 279 matching lines @@
 
         // Deserialize picture
         SkValidatingReadBuffer reader(static_cast<void*>(data.get()), size);
         SkAutoTUnref<SkPicture> readPict(
             SkPicture::CreateFromBuffer(reader));
         REPORTER_ASSERT(reporter, readPict.get());
     }
 
     TestPictureTypefaceSerialization(reporter);
 }