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

ui/gfx/font.h

 // 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.
 
 #ifndef UI_GFX_FONT_H_
 #define UI_GFX_FONT_H_
 
 #include <string>
 
 #include "base/memory/ref_counted.h"
@@ skipping 112 matching lines @@
   // Windows: This handle is owned by the Font object, and should not be
   //          destroyed by the caller.
   // Mac:     The object is owned by the system and should not be released.
   NativeFont GetNativeFont() const;
 #endif
 
   // Raw access to the underlying platform font implementation. Can be
   // 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_;
 };
 
 #ifndef NDEBUG
 GFX_EXPORT std::ostream& operator<<(std::ostream& stream,
                                     const Font::Weight weight);
 #endif
 
 }  // namespace gfx
 
 #endif  // UI_GFX_FONT_H_