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

ui/gfx/font_list.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/font_list.h"
 
 #include "base/lazy_instance.h"
 #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 {
 
 // Font description of the default font set.
 base::LazyInstance<std::string>::Leaky g_default_font_description =
     LAZY_INSTANCE_INITIALIZER;
 
 // The default instance of gfx::FontListImpl.
 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 {
 
 // static
 bool FontList::ParseDescription(const std::string& description,
                                 std::vector<std::string>* families_out,
                                 int* style_out,
                                 int* size_pixels_out,
                                 Font::Weight* weight_out) {
@@ skipping 182 matching lines @@
     g_default_impl.Get() =
         g_default_font_description.Get().empty() ?
             new FontListImpl(Font()) :
             new FontListImpl(g_default_font_description.Get());
     g_default_impl_initialized = true;
   }
 
   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