Make xformer class for SkCSXCanvas, use for draw loopers

Fixes draw looper gms in gbr-8888 config.

Bug: skia:
Change-Id: I0a9306cc0523c82f2ad9516752d79c1d86b1e295
Reviewed-on: https://skia-review.googlesource.com/10644
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
diff --git a/src/core/SkColorSpaceXformer.h b/src/core/SkColorSpaceXformer.h
new file mode 100644
index 0000000..b89fd8a
--- /dev/null
+++ b/src/core/SkColorSpaceXformer.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkColorSpaceXformer_DEFINED
+#define SkColorSpaceXformer_DEFINED
+
+#include "SkColorSpaceXform.h"
+#include "SkImage.h"
+#include "SkShader.h"
+
+class SkColorSpaceXformer : public SkNoncopyable {
+public:
+    static std::unique_ptr<SkColorSpaceXformer> Make(sk_sp<SkColorSpace> dst);
+
+    sk_sp<SkImage> apply(const SkImage* src);
+    const SkPaint* apply(const SkPaint* src);
+    const SkPaint& apply(const SkPaint& src);
+    void apply(SkColor dst[], const SkColor src[], int n);
+
+private:
+    SkColor apply(SkColor srgb);
+    sk_sp<SkShader> apply(const SkShader* shader);
+
+    SkColorSpaceXformer() {}
+
+    sk_sp<SkColorSpace>                fDst;
+    std::unique_ptr<SkColorSpaceXform> fFromSRGB;
+    SkPaint                            fDstPaint;
+};
+
+#endif