Allow the default generic font family settings to find the first available font

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 2844a92e37aa811a9dd023d1d65441be65a5e5da..a4b1de73bb7d398008ad5d7a195cf7684834c4ec 100644
--- a/third_party/WebKit/Source/platform/fonts/FontCache.cpp
+++ b/third_party/WebKit/Source/platform/fonts/FontCache.cpp
@@ -48,6 +48,7 @@
 #include "platform/tracing/web_memory_allocator_dump.h"
 #include "platform/tracing/web_process_memory_dump.h"
 #include "public/platform/Platform.h"
+#include "ui/gfx/font.h"
 #include "wtf/HashMap.h"
 #include "wtf/ListHashSet.h"
 #include "wtf/PtrUtil.h"
@@ -302,6 +303,31 @@ bool FontCache::isPlatformFontAvailable(const FontDescription& fontDescription,
       FontFaceCreationParams(adjustFamilyNameToAvoidUnsupportedFonts(family)),
       checkingAlternateName);
 }
+static bool isFontFamilyAvailable(const String& family,
+                                  SkFontMgr* fontManager) {
+#if OS(LINUX)
+  sk_sp<SkTypeface> typeface(
+      fontManager->legacyCreateTypeface(family.utf8().data(), SkFontStyle()));
+  return typeface;
+#else
+  sk_sp<SkFontStyleSet> set(fontManager->matchFamily(family.utf8().data()));
+  return set && set->count();
+#endif
+}
+
+String FontCache::firstAvailableOrFirst(const String& families) {
+  Vector<String> familyList;
+  families.split(',', familyList);
+  if (familyList.isEmpty())
+    return String();
+  sk_sp<SkFontMgr> fm(SkFontMgr::RefDefault());
+  for (String& family : familyList) {
+    family = family.stripWhiteSpace();
+    if (isFontFamilyAvailable(family, fm.get()))
+      return family;
+  }
+  return familyList.first();
+}
 
 SimpleFontData* FontCache::getNonRetainedLastResortFallbackFont(
     const FontDescription& fontDescription) {