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

chrome/browser/ui/webui/options/font_settings_utils.cc

Index: chrome/browser/ui/webui/options/font_settings_utils.cc
diff --git a/chrome/browser/ui/webui/options/font_settings_utils.cc b/chrome/browser/ui/webui/options/font_settings_utils.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e7e46c2bae16e38eaa466149a03bfb14664fcb9d
--- /dev/null
+++ b/chrome/browser/ui/webui/options/font_settings_utils.cc
@@ -0,0 +1,29 @@
+// Copyright (c) 2016 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 "chrome/browser/ui/webui/options/font_settings_utils.h"
+
+#include "ui/gfx/font.h"
+
+namespace options {
+
+// Returns the first available font if it starts with ",".

[msw, 2016/10/26 20:33:49]

These comments belong with the function declarations in the header.

[kojii, 2016/10/26 22:20:02]

Thank you, not very familiar with Chromium side yet.

+std::string FontSettingsUtilities::ResolveFontList(
+    const std::string& font_name_or_list) {
+  if (!font_name_or_list.empty() && font_name_or_list[0] == ',')
+    return gfx::Font::FirstAvailableOrFirst(font_name_or_list);

[msw, 2016/10/26 20:33:49]

Why aren't we using the standard gfx::FontList codepaths here? Why would this
ignore the other fonts in the list? Having fallbacks is important. If we are
indeed only using the first font, that should probably be part of the function
name, and the reasoning should be justified in a comment.

[kojii, 2016/10/26 22:20:02]

gfx::FontList cascades by the availability of glyphs, but this function needs
the availability of font. If the first available font doesn't have a glyph, it
needs to fallback to the next font specified in CSS.

I'll add comments to clarify.

[msw, 2016/10/27 00:04:18]

Using FontList to just parse the string and then return the primary font name
wouldn't preclude using the CSS fallback mechanism. But I see there may be some
other obstacles to going in that direction...

+  return font_name_or_list;
+}
+
+#if !defined(OS_WIN)
+// Returns the localized name of a font so that settings can find it within the
+// list of system fonts. On Windows, the list of system fonts has names only
+// for the system locale, but the pref value may be in the English name.
+std::string FontSettingsUtilities::MaybeGetLocalizedFontName(

[msw, 2016/10/26 20:33:49]

Ditto to my comments and questions above.

+    const std::string& font_name_or_list) {
+  return ResolveFontList(font_name_or_list);
+}
+#endif
+
+}  // namespace options