Implement support for rendering color emoji on Windows

src/ports/SkScalerContext_win_dw.h

Index: src/ports/SkScalerContext_win_dw.h
diff --git a/src/ports/SkScalerContext_win_dw.h b/src/ports/SkScalerContext_win_dw.h
index 9b2477203644a2b9a2f9473169bf7006c5b66016..98c4910b27f0501d9df0fa7d2e924d371c2bf998 100644
--- a/src/ports/SkScalerContext_win_dw.h
+++ b/src/ports/SkScalerContext_win_dw.h
@@ -14,6 +14,9 @@
 #include "SkTypes.h"
 
 #include <dwrite.h>
+#if SK_HAS_DWRITE_2_H
+#include <dwrite_2.h>
+#endif
 
 class SkGlyph;
 class SkDescriptor;
@@ -42,6 +45,14 @@ private:
                            DWRITE_TEXTURE_TYPE textureType,
                            RECT* bbox);
 
+    bool isColorGlyph(const SkGlyph& glyph);
+
+#if SK_HAS_DWRITE_2_H
+    bool getColorGlyphRun(const SkGlyph& glyph, IDWriteColorGlyphRunEnumerator** colorGlyph);
+
+    void generateColorGlyphImage(const SkGlyph& glyph);
+#endif
+
     SkTDArray<uint8_t> fBits;
     /** The total matrix without the text height scale. */
     SkMatrix fSkXform;
@@ -64,6 +75,10 @@ private:
     DWRITE_RENDERING_MODE fRenderingMode;
     DWRITE_TEXTURE_TYPE fTextureType;
     DWRITE_MEASURING_MODE fMeasuringMode;
+#if SK_HAS_DWRITE_2_H
+    SkTScopedComPtr<IDWriteFactory2> fFactory2;
+    bool fIsColorFont;
+#endif
 };
 
 #endif