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..b6a7ec67ce550bb39e238fc956112321311fdca8 100644
--- a/ui/gfx/font.h
+++ b/ui/gfx/font.h
@@ -130,6 +130,8 @@ class GFX_EXPORT Font {
   // static_cast to a known implementation type if needed.
   PlatformFont* platform_font() const { return platform_font_.get(); }
 
+  static std::string FirstAvailableOrFirst(const std::string&);

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

Add a comment, what's the difference between "first available" and "first"?

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

Is this actually needed as part of the gfx::font api? If this unusual
font-related functionality is only used by blink, and nowhere else in the
codebase, then perhaps this doesn't belong here.

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