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

ui/gfx/font.h

Index: ui/gfx/font.h
diff --git a/ui/gfx/font.h b/ui/gfx/font.h
index e33bb680f6a690de88499a4483a3630a04220fd9..79b153e9cb46023b0f02c8dfe3318b14f6b17285 100644
--- a/ui/gfx/font.h
+++ b/ui/gfx/font.h
@@ -130,6 +130,12 @@ class GFX_EXPORT Font {
   // static_cast to a known implementation type if needed.
   PlatformFont* platform_font() const { return platform_font_.get(); }
 
+  // Returns the first available font name. If there is no available font,
+  // returns the first font name. Empty entries are ignored.
+  // Used by Blink and webui to pick the primary standard/serif/sans/fixed/etc.
+  // fonts from region-specific IDS lists.
+  static std::string FirstAvailableOrFirst(const std::string& font_name_list);

[msw, 2016/10/28 07:05:06]

This probably shouldn't be a Font class member function; I'd add it to new
font_util.h|cc files, maybe to skia_util.h|cc, or perhaps as a static FontList
member (it's somewhat related, but not even used there...) but I've given you
bad advice before, so feel free to ask another gfx owner :)

[kojii, 2016/10/28 07:57:30]

FontList makes perfect sense to me, I was actually wondering which is better.
Thank you for this many round of reviews, please don't call the efforts to seek
for better as bad ;)

+
  private:
   // Wrapped platform font implementation.
   scoped_refptr<PlatformFont> platform_font_;