Add FontCache API for retrieving prioritized fallback fonts

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

Index: third_party/WebKit/Source/platform/fonts/FontCache.cpp
diff --git a/third_party/WebKit/Source/platform/fonts/FontCache.cpp b/third_party/WebKit/Source/platform/fonts/FontCache.cpp
index 462f0d04ff0cd9443d31061f85b23e7733a538f1..679c3f06a1cab479bc39e23f0487584efec51f64 100644
--- a/third_party/WebKit/Source/platform/fonts/FontCache.cpp
+++ b/third_party/WebKit/Source/platform/fonts/FontCache.cpp
@@ -194,6 +194,40 @@ SimpleFontData* FontCache::getNonRetainedLastResortFallbackFont(const FontDescri
     return getLastResortFallbackFont(fontDescription, DoNotRetain).leakRef();
 }
 
+template <FontFallbackPriority fallbackPriority>
+const Vector<AtomicString>& FontCache::initAndGetfontListForFallbackPriority(const FontDescription fontDescription)
+{
+    DEFINE_STATIC_LOCAL(Vector<AtomicString>, fontsList, ());
+    DEFINE_STATIC_LOCAL(bool, fontsListInitialized, (false));
+    if (!fontsListInitialized) {

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

Blink seems to prefer the early-out

if (fontsListInitialized)
    return fontsList;

to reduce subsequent indentation and (debatably) readability, I don't feel
strongly for short methods like this though.

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

Changed to early-return.

+        for (auto fontCandidate : platformFontListForFallbackPriority(fallbackPriority)) {
+            if (isPlatformFontAvailable(fontDescription, fontCandidate)) {
+                fontsList.append(fontCandidate);
+            }
+        }
+        fontsListInitialized = true;
+    }
+    return fontsList;
+

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

rm blank

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

Done.

+}
+
+const Vector<AtomicString>& FontCache::fontListForFallbackPriority(const FontDescription& fontDescription, FontFallbackPriority fallbackPriority)
+{
+    // Explicit template instantiations for valid values.
+    switch (fallbackPriority) {
+    case FontFallbackPriority::Symbols:
+        return initAndGetfontListForFallbackPriority<FontFallbackPriority::Symbols>(fontDescription);
+    case FontFallbackPriority::Math:
+        return initAndGetfontListForFallbackPriority<FontFallbackPriority::Math>(fontDescription);
+    case FontFallbackPriority::EmojiText:
+        return initAndGetfontListForFallbackPriority<FontFallbackPriority::EmojiText>(fontDescription);
+    case FontFallbackPriority::EmojiEmoji:
+        return initAndGetfontListForFallbackPriority<FontFallbackPriority::EmojiEmoji>(fontDescription);
+    default:
+        RELEASE_ASSERT_NOT_REACHED();

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

This would require a EXPECT_DEATH in a gtest checking for Invalid and Text
values...

+    }
+}
+
 void FontCache::releaseFontData(const SimpleFontData* fontData)
 {
     ASSERT(gFontDataCache);