Add UMAs for numerical approximation of table-based transfer functions.

ui/gfx/skia_color_space_util.h

Index: ui/gfx/skia_color_space_util.h
diff --git a/ui/gfx/skia_color_space_util.h b/ui/gfx/skia_color_space_util.h
index da132b9d9c5773a4bbe084d58ec95da091e00ccb..22183101706705b6b208d5c6a5afdc6f1b4ea0d9 100644
--- a/ui/gfx/skia_color_space_util.h
+++ b/ui/gfx/skia_color_space_util.h
@@ -6,6 +6,7 @@
 #define UI_GFX_SKIA_COLOR_SPACE_UTIL_H_
 
 #include "third_party/skia/include/core/SkColorSpace.h"
+#include "third_party/skia/include/core/SkICC.h"
 #include "ui/gfx/gfx_export.h"
 
 namespace gfx {
@@ -22,6 +23,14 @@ SkTransferFnsApproximatelyCancel(const SkColorSpaceTransferFn& a,
 bool GFX_EXPORT
 SkTransferFnIsApproximatelyIdentity(const SkColorSpaceTransferFn& fn);
 
+void GFX_EXPORT SkApproximateTransferFn(const float* x,
+                                        const float* t,
+                                        size_t n,
+                                        SkColorSpaceTransferFn* fn,
+                                        float* error,
+                                        bool* nonlinear_fit_converged,
+                                        bool* linear_fit_succeeded);
+
 bool GFX_EXPORT SkMatrixIsApproximatelyIdentity(const SkMatrix44& m);
 
 }  // namespace gfx