Introduce GrColorSpaceXform, for gamut conversion on textures

src/gpu/GrTextureToYUVPlanes.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 "GrTextureToYUVPlanes.h"
 #include "effects/GrSimpleTextureEffect.h"
 #include "effects/GrYUVEffect.h"
@@ skipping 14 matching lines @@
     SkScalar xScale = SkIntToScalar(src->width()) / dstW / src->width();
     SkScalar yScale = SkIntToScalar(src->height()) / dstH / src->height();
     GrTextureParams::FilterMode filter;
     if (dstW == src->width() && dstW == src->height()) {
         filter = GrTextureParams::kNone_FilterMode;
     } else {
         filter = GrTextureParams::kBilerp_FilterMode;
     }
 
     sk_sp<GrFragmentProcessor> fp(
-            GrSimpleTextureEffect::Make(src, SkMatrix::MakeScale(xScale, yScale), filter));
+            GrSimpleTextureEffect::Make(src, nullptr, SkMatrix::MakeScale(xScale, yScale), filter));
     if (!fp) {
         return false;
     }
     fp = proc(std::move(fp), colorSpace);
     if (!fp) {
         return false;
     }
     GrPaint paint;
     paint.setPorterDuffXPFactory(SkXfermode::kSrc_Mode);
     paint.addColorFragmentProcessor(std::move(fp));
@@ skipping 175 matching lines @@
                 if (!tex->readPixels(0, 0, sizes[2].fWidth, sizes[2].fHeight,
                                      kAlpha_8_GrPixelConfig, planes[2], rowBytes[2])) {
                     return false;
                 }
                 return true;
             }
         }
     }
     return false;
 }