use special-image for imagefilters and save/restore layer

src/core/SkDevice.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkColorFilter.h"
 #include "SkDevice.h"
 #include "SkDraw.h"
@@ skipping 203 matching lines @@
 
         path.rewind();
         path.addPoly(quad, 4, true);
         path.setConvexity(SkPath::kConvex_Convexity);
         this->drawPath(draw, path, pnt, nullptr, true);
     }
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
+void SkBaseDevice::drawSpecial(const SkDraw&, SkSpecialImage*, int x, int y, const SkPaint&) {}
+sk_sp<SkSpecialImage> SkBaseDevice::makeSpecial(const SkBitmap&) { return nullptr; }
+sk_sp<SkSpecialImage> SkBaseDevice::makeSpecial(const SkImage*) { return nullptr; }
+sk_sp<SkSpecialImage> SkBaseDevice::asSpecial() { return nullptr; }
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
 bool SkBaseDevice::readPixels(const SkImageInfo& info, void* dstP, size_t rowBytes, int x, int y) {
 #ifdef SK_DEBUG
     SkASSERT(info.width() > 0 && info.height() > 0);
     SkASSERT(dstP);
     SkASSERT(rowBytes >= info.minRowBytes());
     SkASSERT(x >= 0 && y >= 0);
 
     const SkImageInfo& srcInfo = this->imageInfo();
     SkASSERT(x + info.width() <= srcInfo.width());
     SkASSERT(y + info.height() <= srcInfo.height());
@@ skipping 304 matching lines @@
 
     // Also log filter quality independent scale factor.
     SK_HISTOGRAM_ENUMERATION("DrawScaleFactor.AnyFilterQuality", scaleFactor,
                              kLast_ScaleFactor + 1);
 
     // Also log an overall histogram of filter quality.
     SK_HISTOGRAM_ENUMERATION("FilterQuality", filterQuality, kLast_SkFilterQuality + 1);
 #endif
 }