Add plumbing in blink to allow overriding the default font collection.

third_party/WebKit/public/web/win/WebFontRendering.h

Index: third_party/WebKit/public/web/win/WebFontRendering.h
diff --git a/third_party/WebKit/public/web/win/WebFontRendering.h b/third_party/WebKit/public/web/win/WebFontRendering.h
index 5c7c3836d7c3e7f6d282b4fc8bb9029c49cce3d1..ffe5179bf5fa4d373f0a06738a67c77dac1c2cb4 100644
--- a/third_party/WebKit/public/web/win/WebFontRendering.h
+++ b/third_party/WebKit/public/web/win/WebFontRendering.h
@@ -6,17 +6,17 @@
 #define WebFontRendering_h
 
 #include "public/platform/WebCommon.h"
-#include <SkFontHost.h>
+#include "third_party/skia/include/core/SkFontHost.h"
 
+class SkFontMgr;
 class SkTypeface;
-struct IDWriteFactory;
 
 namespace blink {
 
 class WebFontRendering {
 public:
     BLINK_EXPORT static void setUseDirectWrite(bool);
-    BLINK_EXPORT static void setDirectWriteFactory(IDWriteFactory*);
+    BLINK_EXPORT static void setSkiaFontManager(SkFontMgr*);
     BLINK_EXPORT static void setDeviceScaleFactor(float);
     BLINK_EXPORT static void setUseSubpixelPositioning(bool);
     BLINK_EXPORT static void addSideloadedFontForTesting(SkTypeface*);