linux: Add some font-family-related FontRenderParams tests.

ui/gfx/test/fontconfig_util_linux.h

Index: ui/gfx/test/fontconfig_util_linux.h
diff --git a/ui/gfx/test/fontconfig_util_linux.h b/ui/gfx/test/fontconfig_util_linux.h
index a1b91fa459d8ab0607376d1c0d1c5e44e04edff0..9fa66b28209d22deac78cb80bc9b542201b732d7 100644
--- a/ui/gfx/test/fontconfig_util_linux.h
+++ b/ui/gfx/test/fontconfig_util_linux.h
@@ -54,6 +54,10 @@ std::string CreateFontconfigTestStanza(const std::string& name,
                                        const std::string& type,
                                        const std::string& value);
 
+// Returns a Fontconfig <alias> stanza.
+std::string CreateFontconfigAliasStanza(const std::string& original_family,
+                                        const std::string& preferred_family);
+
 }  // namespace gfx
 
 #endif  // UI_GFX_TEST_FONTCONFIG_UTIL_LINUX_H_