Implement onMatchFamilyStyleCharacter for DirectWrite.

src/utils/win/SkDWrite.h

Index: src/utils/win/SkDWrite.h
diff --git a/src/utils/win/SkDWrite.h b/src/utils/win/SkDWrite.h
index 5b566730e5db6a24ecd6eda4a2bcdcc80d471c82..1716b837856006195af0f34fd31fd84884aae695 100644
--- a/src/utils/win/SkDWrite.h
+++ b/src/utils/win/SkDWrite.h
@@ -9,6 +9,7 @@
 #define SkDWrite_DEFINED
 
 #include "SkTemplates.h"
+#include "SkFontStyle.h"
 
 #include <dwrite.h>
 #include <winsdkver.h>
@@ -80,4 +81,28 @@ public:
     const T* operator->() const { return reinterpret_cast<const T*>(fData); }
 };
 
+////////////////////////////////////////////////////////////////////////////////
+// Style conversion
+
+struct DWriteStyle {
+    explicit DWriteStyle(const SkFontStyle& pattern) {
+        switch (pattern.slant()) {
+        case SkFontStyle::kUpright_Slant:
+            fSlant = DWRITE_FONT_STYLE_NORMAL;
+            break;
+        case SkFontStyle::kItalic_Slant:
+            fSlant = DWRITE_FONT_STYLE_ITALIC;
+            break;
+        default:
+            SkASSERT(false);
+        }
+
+        fWeight = (DWRITE_FONT_WEIGHT)pattern.weight();
+        fWidth = (DWRITE_FONT_STRETCH)pattern.width();
+    }
+    DWRITE_FONT_STYLE fSlant;
+    DWRITE_FONT_WEIGHT fWeight;
+    DWRITE_FONT_STRETCH fWidth;
+};
+
 #endif