[DirectWrite] Limit noSubpixelForSmallSizeFont to low-DPI

Source/platform/fonts/FontCache.h

Index: Source/platform/fonts/FontCache.h
diff --git a/Source/platform/fonts/FontCache.h b/Source/platform/fonts/FontCache.h
index 53f81eb8c7defd5dc90120b92a931b32458ddc4d..000b48b0c60727545c31ae386424a9153c943943 100644
--- a/Source/platform/fonts/FontCache.h
+++ b/Source/platform/fonts/FontCache.h
@@ -104,8 +104,10 @@ public:
     bool useSubpixelPositioning() const { return s_useSubpixelPositioning; }
     SkFontMgr* fontManager() { return m_fontManager.get(); }
     static bool useDirectWrite() { return s_useDirectWrite; }
+    static float deviceScaleFactor() { return s_deviceScaleFactor; }
     static void setUseDirectWrite(bool useDirectWrite) { s_useDirectWrite = useDirectWrite; }
     static void setDirectWriteFactory(IDWriteFactory* factory) { s_directWriteFactory = factory; }
+    static void setDeviceScaleFactor(float deviceScaleFactor) { s_deviceScaleFactor = deviceScaleFactor; }
     static void setUseSubpixelPositioning(bool useSubpixelPositioning) { s_useSubpixelPositioning = useSubpixelPositioning; }
     static void addSideloadedFontForTesting(SkTypeface*);
 #endif
@@ -162,6 +164,7 @@ private:
     OwnPtr<SkFontMgr> m_fontManager;
     static bool s_useDirectWrite;
     static IDWriteFactory* s_directWriteFactory;
+    static float s_deviceScaleFactor;
     static bool s_useSubpixelPositioning;
     static HashMap<String, RefPtr<SkTypeface> >* s_sideloadedFonts;
 #endif