Add bilerp filtering.

bench/SkLinearBitmapPipelineBench.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include <memory>
 #include "SkColor.h"
 #include "SkLinearBitmapPipeline.h"
@@ skipping 116 matching lines @@
         }
         return name;
     }
 
     void onDraw(int loops, SkCanvas*) override {
         int width = fSrcSize.fWidth;
         int height = fSrcSize.fHeight;
 
         SkAutoTMalloc<SkPM4f> FPbuffer(width*height);
 
-        SkLinearBitmapPipeline pipeline{fInvert, fXTile, fYTile, fInfo, fBitmap.get(), };
+        SkFilterQuality filterQuality;
+        if (fUseBilerp) {
+            filterQuality = SkFilterQuality::kLow_SkFilterQuality;
+        } else {
+            filterQuality = SkFilterQuality::kNone_SkFilterQuality;
+        }
+
+        SkLinearBitmapPipeline pipeline{
+            fInvert, filterQuality, fXTile, fYTile, fInfo, fBitmap.get() };
 
         int count = 100;
 
         for (int n = 0; n < 1000*loops; n++) {
             pipeline.shadeSpan4f(3, 6, FPbuffer, count);
         }
     }
 };
 
 struct SkBitmapFPOrigShader : public CommonBitmapFPBenchmark {
@@ skipping 129 matching lines @@
     SkShader::kClamp_TileMode, SkShader::kClamp_TileMode);)
 
 DEF_BENCH(return new SkBitmapFPGeneral(
     srcSize, kLinear_SkColorProfileType, mR, true,
     SkShader::kClamp_TileMode, SkShader::kClamp_TileMode);)
 
 DEF_BENCH(return new SkBitmapFPOrigShader(
     srcSize, kLinear_SkColorProfileType, mR, true,
     SkShader::kClamp_TileMode, SkShader::kClamp_TileMode);)