Introduce GrColorSpaceXform, for gamut conversion on textures

include/gpu/GrColorSpaceXform.h

Index: include/gpu/GrColorSpaceXform.h
diff --git a/include/gpu/GrColorSpaceXform.h b/include/gpu/GrColorSpaceXform.h
new file mode 100644
index 0000000000000000000000000000000000000000..ea90739fd2f0354f931de32c5b5112db4163aa5a
--- /dev/null
+++ b/include/gpu/GrColorSpaceXform.h
@@ -0,0 +1,31 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrColorSpaceXform_DEFINED
+#define GrColorSpaceXform_DEFINED
+
+#include "SkMatrix44.h"
+#include "SkRefCnt.h"
+
+class SkColorSpace;
+
+ /**
+  * Represents a color gamut transformation (as a 4x4 color matrix)
+  */
+class GrColorSpaceXform : public SkRefCnt {
+public:
+    GrColorSpaceXform(const SkMatrix44& srcToDst) : fSrcToDst(srcToDst) {}
+
+    static sk_sp<GrColorSpaceXform> Make(SkColorSpace* src, SkColorSpace* dst);
+
+    const SkMatrix44& srcToDst() { return fSrcToDst; }
+
+private:
+    SkMatrix44 fSrcToDst;
+};
+
+#endif