Glyph positions maintain 32 bit integer part.

include/core/SkFixed.h

Index: include/core/SkFixed.h
diff --git a/include/core/SkFixed.h b/include/core/SkFixed.h
index f3326618433dbaa060f5f950ea85d101489e27da..9dbd806ac9aa57012d82f35ecf9aa58b8eca1c45 100644
--- a/include/core/SkFixed.h
+++ b/include/core/SkFixed.h
@@ -150,4 +150,17 @@ typedef int64_t SkFixed3232;   // 32.32
 
 #define SkScalarToFixed3232(x)    SkFloatToFixed3232(x)
 
+///////////////////////////////////////////////////////////////////////////////
+
+// 64bits wide, with a 16bit bias. Useful when accumulating lots of 16.16 so
+// we don't overflow along the way
+typedef int64_t Sk48Dot16;
+
+static inline float Sk48Dot16ToScalar(Sk48Dot16 x) {
+    return static_cast<float>(x * 1.5258789e-5);  // x * (1.0f / (1 << 16))
+}
+#define SkFloatTo48Dot16(x)       (static_cast<Sk48Dot16>((x) * (1 << 16)))
+
+#define SkScalarTo48Dot16(x)      SkFloatTo48Dot16(x)
+
 #endif