Add FontCache API for retrieving prioritized fallback fonts

third_party/WebKit/Source/platform/fonts/mac/FontCacheMac.mm

Index: third_party/WebKit/Source/platform/fonts/mac/FontCacheMac.mm
diff --git a/third_party/WebKit/Source/platform/fonts/mac/FontCacheMac.mm b/third_party/WebKit/Source/platform/fonts/mac/FontCacheMac.mm
index 0ea373417959f4aa4d374ba9457769928ce2d893..325081a9273fe3d3b6963cbfaef59cebb294dbc4 100644
--- a/third_party/WebKit/Source/platform/fonts/mac/FontCacheMac.mm
+++ b/third_party/WebKit/Source/platform/fonts/mac/FontCacheMac.mm
@@ -53,6 +53,10 @@
 
 namespace blink {
 
+const char* kColorEmojiFontsMac[] = { "Apple Color Emoji" };

[wkorman, 2016/01/25 23:38:16]

Is there a useful documentation comment we can add here and in Skia below re:
what url/doc/approach we used to determine these constants? To help eng in
future should they need updating/revisiting.

[drott, 2016/02/02 17:28:28]

Added comments on how to determine/update those, to the best of my knowledge.
Unfortunately, documentation on this is sparse.

+const char* kTextEmojiFontsMac[] = { "Hiragino Kaku Gothic ProN", "Zapf Dingbats", "Apple Symbols" };
+const char* kSymbolsAndMathFontsMac[] = { "Menlo", "Arial Unicode MS" };
+
 static void invalidateFontCache()
 {
     if (!isMainThread()) {
@@ -216,4 +220,29 @@ PassOwnPtr<FontPlatformData> FontCache::createFontPlatformData(const FontDescrip
     return platformData.release();
 }
 
+
+const Vector<AtomicString> FontCache::platformFontListForFallbackPriority(FontFallbackPriority fallbackPriority) const
+{
+    Vector<AtomicString> returnVector;
+    switch (fallbackPriority) {
+    case FontFallbackPriority::EmojiEmoji:
+        for (size_t i = 0; i < WTF_ARRAY_LENGTH(kColorEmojiFontsMac); ++i)
+            returnVector.append(kColorEmojiFontsMac[i]);
+        break;
+    case FontFallbackPriority::EmojiText:
+        for (size_t i = 0; i < WTF_ARRAY_LENGTH(kTextEmojiFontsMac); ++i)
+            returnVector.append(kTextEmojiFontsMac[i]);
+        break;
+    case FontFallbackPriority::Math:
+    case FontFallbackPriority::Symbols:
+        for (size_t i = 0; i < WTF_ARRAY_LENGTH(kSymbolsAndMathFontsMac); ++i)
+            returnVector.append(kSymbolsAndMathFontsMac[i]);
+        break;
+    default:
+        ASSERT_NOT_REACHED();
+    }
+    return returnVector;
+}
+
+
 } // namespace blink