Templatize SkToXXX.

include/core/SkTypes.h

Index: include/core/SkTypes.h
diff --git a/include/core/SkTypes.h b/include/core/SkTypes.h
index 1051f08ceaa807840cc361eb212e47377fed1ab2..d7a791163be3617b4c414d3f30d4da0982b141d0 100644
--- a/include/core/SkTypes.h
+++ b/include/core/SkTypes.h
@@ -256,27 +256,20 @@ typedef unsigned U16CPU;
  */
 typedef uint8_t SkBool8;
 
-#ifdef SK_DEBUG
-    SK_API int8_t      SkToS8(intmax_t);
-    SK_API uint8_t     SkToU8(uintmax_t);
-    SK_API int16_t     SkToS16(intmax_t);
-    SK_API uint16_t    SkToU16(uintmax_t);
-    SK_API int32_t     SkToS32(intmax_t);
-    SK_API uint32_t    SkToU32(uintmax_t);
-    SK_API int         SkToInt(intmax_t);
-    SK_API unsigned    SkToUInt(uintmax_t);
-    SK_API size_t      SkToSizeT(uintmax_t);
-#else
-    #define SkToS8(x)   ((int8_t)(x))
-    #define SkToU8(x)   ((uint8_t)(x))
-    #define SkToS16(x)  ((int16_t)(x))
-    #define SkToU16(x)  ((uint16_t)(x))
-    #define SkToS32(x)  ((int32_t)(x))
-    #define SkToU32(x)  ((uint32_t)(x))
-    #define SkToInt(x)  ((int)(x))
-    #define SkToUInt(x) ((unsigned)(x))
-    #define SkToSizeT(x) ((size_t)(x))
-#endif
+#include "../private/SkTFitsIn.h"
+template <typename D, typename S> D SkTo(S s) {
+    SkASSERT(SkTFitsIn<D>(s));
+    return static_cast<D>(s);
+}
+#define SkToS8(x)    SkTo<int8_t>(x)
+#define SkToU8(x)    SkTo<uint8_t>(x)
+#define SkToS16(x)   SkTo<int16_t>(x)
+#define SkToU16(x)   SkTo<uint16_t>(x)
+#define SkToS32(x)   SkTo<int32_t>(x)
+#define SkToU32(x)   SkTo<uint32_t>(x)
+#define SkToInt(x)   SkTo<int>(x)
+#define SkToUInt(x)  SkTo<unsigned>(x)
+#define SkToSizeT(x) SkTo<size_t>(x)
 
 /** Returns 0 or 1 based on the condition
 */