Add bilerp filtering.

tests/SkLinearBitmapPipelineTest.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 "SkLinearBitmapPipeline.h"
 
 #include "SkColor.h"
 
@@ skipping 23 matching lines @@
 
     SkMatrix m = SkMatrix::I();
     //m.setRotate(30.0f, 1.0f, 1.0f);
     SkMatrix invert;
     bool trash = m.invert(&invert);
     sk_ignore_unused_variable(trash);
 
     const SkImageInfo info =
         SkImageInfo::MakeN32Premul(width, height, kLinear_SkColorProfileType);
 
-    SkLinearBitmapPipeline pipeline{invert, SkShader::kClamp_TileMode,
+    SkLinearBitmapPipeline pipeline{invert, kNone_SkFilterQuality, SkShader::kClamp_TileMode,
                                     SkShader::kClamp_TileMode, info, bitmap};
 
     int count = 10;
 
     pipeline.shadeSpan4f(3, 6, FPbuffer, count);
 
     Pixel* pixelBuffer = (Pixel*)FPbuffer;
     for (int i = 0; i < count; i++) {
         printf("i: %d - (%g, %g, %g, %g)\n", i,
                pixelBuffer[i][0] * 255.0f,
                pixelBuffer[i][1] * 255.0f,
                pixelBuffer[i][2] * 255.0f,
                pixelBuffer[i][3] * 255.0f);
     }
 
     delete [] bitmap;
     delete [] FPbuffer;
 }