Set the font family for the "system-ui" generic font family on Linux

third_party/WebKit/Source/web/linux/WebFontRendering.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 71 matching lines @@
 {
     FontDescription::setSubpixelPositioning(useSubpixelPositioning);
 }
 
 // static
 void WebFontRendering::setDefaultFontSize(int size)
 {
     LayoutThemeFontProvider::setDefaultFontSize(size);
 }
 
+// static
+void WebFontRendering::setSystemFontFamily(const char* name)
+{
+    FontCache::setSystemFontFamily(name);
+}
+
 } // namespace blink