Update our SK_ARRAY_COUNT macro to account for when pointers are passed.

include/core/SkTypes.h

Index: include/core/SkTypes.h
diff --git a/include/core/SkTypes.h b/include/core/SkTypes.h
index a1719f89e10e4f86a256c6aa178e94e8651e3c9e..01736566457a07fa7c9b2e1a68baeff874f922db 100644
--- a/include/core/SkTypes.h
+++ b/include/core/SkTypes.h
@@ -296,9 +296,28 @@ static inline bool SkIsU16(long x) {
     #define SK_OFFSETOF(type, field)    (size_t)((char*)&(((type*)1)->field) - (char*)1)
 #endif
 
+// The SK_ARRAY_COUNT(arr) macro returns the # of elements in an array arr.
+// The expression is a compile-time constant, and therefore can be
+// used in defining new arrays, for example.  If you use SK_ARRAY_COUNT on
+// a pointer by mistake, you will get a compile-time error.
+//
+// This template function declaration is used in defining SK_ARRAY_COUNT.
+// Note that the function doesn't need an implementation, as we only
+// use its type.
+template <typename T, size_t N>
+char (&ArraySizeHelper(T (&array)[N]))[N];
+
+// That gcc wants both of these prototypes seems mysterious. VC, for
+// its part, can't decide which to use (another mystery). Matching of
+// template overloads: the final frontier.
+#ifndef _MSC_VER
+template <typename T, size_t N>
+char (&ArraySizeHelper(const T (&array)[N]))[N];
+#endif
+
 /** Returns the number of entries in an array (not a pointer)
 */
-#define SK_ARRAY_COUNT(array)       (sizeof(array) / sizeof(array[0]))
+#define SK_ARRAY_COUNT(array) (sizeof(::ArraySizeHelper(array)))
 
 #define SkAlign2(x)     (((x) + 1) >> 1 << 1)
 #define SkIsAlign2(x)   (0 == ((x) & 1))