Add SkColorSpaceXform to the public API

tests/ColorSpaceXformTest.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 "Resources.h"
 #include "SkCodec.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
 #include "SkColorSpace.h"
 #include "SkColorSpace_Base.h"
-#include "SkColorSpaceXform.h"
+#include "SkColorSpaceXform_Base.h"
 #include "Test.h"
 
 class ColorSpaceXformTest {
 public:
     static std::unique_ptr<SkColorSpaceXform> CreateIdentityXform(const sk_sp<SkGammas>& gammas) {
         // Logically we can pass any matrix here.  For simplicty, pass I(), i.e. D50 XYZ gamut.
         sk_sp<SkColorSpace> space(new SkColorSpace_Base(
                 nullptr, kNonStandard_SkGammaNamed, gammas, SkMatrix::I(), nullptr));
 
         // Use special testing entry point, so we don't skip the xform, even though src == dst.
@@ skipping 153 matching lines @@
     // this ICC profile has a CLUT in it
     const SkString filename(GetResourcePath("icc_profiles/upperRight.icc"));
     sk_sp<SkData> iccData = SkData::MakeFromFileName(filename.c_str());
     REPORTER_ASSERT_MESSAGE(r, iccData, "upperRight.icc profile required for test");
     sk_sp<SkColorSpace> srcSpace = SkColorSpace::NewICC(iccData->bytes(), iccData->size());
     sk_sp<SkColorSpace> dstSpace = SkColorSpace::NewNamed(SkColorSpace::kSRGB_Named);
     auto xform = SkColorSpaceXform::New(srcSpace.get(), dstSpace.get());
     xform->apply(dst.get(), src.get(), len, SkColorSpaceXform::kRGBA_8888_ColorFormat,
                  SkColorSpaceXform::kRGBA_8888_ColorFormat, kUnpremul_SkAlphaType);
 }