Revert of change all factories to return their base-class

samplecode/SampleUnpremul.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 "gm.h"
 
 #include "sk_tool_utils.h"
@@ skipping 65 matching lines @@
     }
 
     void onDrawBackground(SkCanvas* canvas) override {
         sk_tool_utils::draw_checkerboard(canvas, 0xFFCCCCCC, 0xFFFFFFFF, 12);
     }
 
     void onDrawContent(SkCanvas* canvas) override {
         SkPaint paint;
         paint.setAntiAlias(true);
         paint.setTextSize(SkIntToScalar(24));
-        SkAutoTUnref<SkDrawLooper> looper(
+        SkAutoTUnref<SkBlurDrawLooper> looper(
             SkBlurDrawLooper::Create(SK_ColorBLUE,
                                      SkBlurMask::ConvertRadiusToSigma(SkIntToScalar(2)),
                                      0, 0));
         paint.setLooper(looper);
         SkScalar height = paint.getFontMetrics(nullptr);
         if (!fDecodeSucceeded) {
             SkString failure;
             if (fResPath.size() == 0) {
                 failure.printf("resource path is required!");
             } else {
@@ skipping 91 matching lines @@
 
     typedef SampleView INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static SkView* MyFactory() {
     return new UnpremulView(GetResourcePath());
 }
 static SkViewRegister reg(MyFactory);