Add FontCache API for retrieving prioritized fallback fonts

third_party/WebKit/Source/platform/fonts/FontCache.h

Index: third_party/WebKit/Source/platform/fonts/FontCache.h
diff --git a/third_party/WebKit/Source/platform/fonts/FontCache.h b/third_party/WebKit/Source/platform/fonts/FontCache.h
index 1b83f7de4b67e8da6b8d81a40b1c935b0e982c66..68d9c493c5943722afe931612459930a572be97e 100644
--- a/third_party/WebKit/Source/platform/fonts/FontCache.h
+++ b/third_party/WebKit/Source/platform/fonts/FontCache.h
@@ -34,6 +34,7 @@
 #include "platform/fonts/FallbackListCompositeKey.h"
 #include "platform/fonts/FontCacheKey.h"
 #include "platform/fonts/FontFaceCreationParams.h"
+#include "platform/fonts/FontFallbackPriority.h"
 #include "wtf/Allocator.h"
 #include "wtf/Forward.h"
 #include "wtf/HashMap.h"
@@ -86,6 +87,8 @@ public:
     SimpleFontData* getNonRetainedLastResortFallbackFont(const FontDescription&);
     bool isPlatformFontAvailable(const FontDescription&, const AtomicString&);
 
+    const Vector<AtomicString>& fontListForFallbackPriority(const FontDescription&, FontFallbackPriority);
+
     // Returns the ShapeCache instance associated with the given cache key.
     // Creates a new instance as needed and as such is guaranteed not to return
     // a nullptr. Instances are managed by FontCache and are only guaranteed to
@@ -172,6 +175,11 @@ private:
 
     PassRefPtr<SimpleFontData> fallbackOnStandardFontStyle(const FontDescription&, UChar32);
 
+    template <FontFallbackPriority fallbackPriority>
+    const Vector<AtomicString>& initAndGetFontListForFallbackPriority(const FontDescription&);
+
+    const Vector<AtomicString> platformFontListForFallbackPriority(FontFallbackPriority) const;
+
     // Don't purge if this count is > 0;
     int m_purgePreventCount;