Revert of change all factories to return their base-class

src/effects/SkDisplacementMapEffect.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 "SkDisplacementMapEffect.h"
 #include "SkDevice.h"
 #include "SkReadBuffer.h"
@@ skipping 146 matching lines @@
     default:
         break;
     }
     return false;
 }
 
 } // end namespace
 
 ///////////////////////////////////////////////////////////////////////////////
 
-SkImageFilter* SkDisplacementMapEffect::Create(ChannelSelectorType xChannelSelector,
-                                               ChannelSelectorType yChannelSelector,
-                                               SkScalar scale,
-                                               SkImageFilter* displacement,
-                                               SkImageFilter* color,
-                                               const CropRect* cropRect) {
+SkDisplacementMapEffect* SkDisplacementMapEffect::Create(ChannelSelectorType xChannelSelector,
+                                                         ChannelSelectorType yChannelSelector,
+                                                         SkScalar scale,
+                                                         SkImageFilter* displacement,
+                                                         SkImageFilter* color,
+                                                         const CropRect* cropRect) {
     if (!channel_selector_type_is_valid(xChannelSelector) ||
         !channel_selector_type_is_valid(yChannelSelector)) {
         return nullptr;
     }
 
     SkImageFilter* inputs[2] = { displacement, color };
     return new SkDisplacementMapEffect(xChannelSelector, yChannelSelector, scale, inputs, cropRect);
 }
 
 SkDisplacementMapEffect::SkDisplacementMapEffect(ChannelSelectorType xChannelSelector,
@@ skipping 458 matching lines @@
                                        const GrGLSLCaps&, GrProcessorKeyBuilder* b) {
     const GrDisplacementMapEffect& displacementMap = proc.cast<GrDisplacementMapEffect>();
 
     uint32_t xKey = displacementMap.xChannelSelector();
     uint32_t yKey = displacementMap.yChannelSelector() << kChannelSelectorKeyBits;
 
     b->add32(xKey | yKey);
 }
 #endif