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

ui/gfx/font_list.cc

Index: ui/gfx/font_list.cc
diff --git a/ui/gfx/font_list.cc b/ui/gfx/font_list.cc
index 235778510031e2c9f817dce5f906fcb042c93fde..4ff43eccd302f0a351192f0b1b95b66f4052b317 100644
--- a/ui/gfx/font_list.cc
+++ b/ui/gfx/font_list.cc
@@ -8,6 +8,8 @@
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
+#include "third_party/skia/include/core/SkTypeface.h"
+#include "third_party/skia/include/ports/SkFontMgr.h"
 #include "ui/gfx/font_list_impl.h"
 
 namespace {
@@ -21,6 +23,17 @@ base::LazyInstance<scoped_refptr<gfx::FontListImpl> >::Leaky g_default_impl =
     LAZY_INSTANCE_INITIALIZER;
 bool g_default_impl_initialized = false;
 
+bool IsFontFamilyAvailable(const std::string& family, SkFontMgr* fontManager) {
+#if defined(OS_LINUX)
+  sk_sp<SkTypeface> typeface(
+      fontManager->legacyCreateTypeface(family.c_str(), SkFontStyle()));
+  return typeface;
+#else
+  sk_sp<SkFontStyleSet> set(fontManager->matchFamily(family.c_str()));
+  return set && set->count();
+#endif
+}
+
 }  // namespace
 
 namespace gfx {
@@ -223,4 +236,20 @@ const scoped_refptr<FontListImpl>& FontList::GetDefaultImpl() {
   return g_default_impl.Get();
 }
 
+// static
+std::string FontList::FirstAvailableOrFirst(const std::string& font_name_list) {
+  std::vector<std::string> families = base::SplitString(
+      font_name_list, ",", base::TRIM_WHITESPACE, base::SPLIT_WANT_NONEMPTY);
+  if (families.empty())
+    return std::string();
+  if (families.size() == 1)
+    return families[0];
+  sk_sp<SkFontMgr> fm(SkFontMgr::RefDefault());
+  for (const auto& family : families) {
+    if (IsFontFamilyAvailable(family, fm.get()))
+      return family;
+  }
+  return families[0];
+}
+
 }  // namespace gfx