Add new module for distance field generation.

src/core/SkDistanceFieldGen.h

Index: src/core/SkDistanceFieldGen.h
diff --git a/src/core/SkDistanceFieldGen.h b/src/core/SkDistanceFieldGen.h
new file mode 100755
index 0000000000000000000000000000000000000000..1a2c7c70d45f3c2ea1bdb3ca593dd008bc9575d2
--- /dev/null
+++ b/src/core/SkDistanceFieldGen.h
@@ -0,0 +1,16 @@
+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#ifndef SkDistanceFieldGen_DEFINED
+#define SkDistanceFieldGen_DEFINED
+
+// this assumes the client has already allocated the necessary space in distanceField
+bool SkGenerateDistanceFieldFromImage(unsigned char* distanceField,
+                                      unsigned char* image,
+                                      int w, int h,
+                                      int distanceMagnitude);
+
+#endif