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

ui/gfx/font_unittest.cc

 // 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.
 
 #include "ui/gfx/font.h"
 
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 177 matching lines @@
 TEST_F(FontTest, DeriveKeepsOriginalSizeIfHeightOk) {
   Font cf("Arial", 8);
   // The minimum font size is set to 5 in browser_main.cc.
   ScopedMinimumFontSizeCallback minimum_size(5);
 
   Font derived_font = cf.Derive(-2, cf.GetStyle(), cf.GetWeight());
   EXPECT_EQ(6, derived_font.GetFontSize());
 }
 #endif  // defined(OS_WIN)
 
+TEST_F(FontTest, FirstAvailableOrFirst) {
+  EXPECT_TRUE(Font::FirstAvailableOrFirst("").empty());
+  EXPECT_TRUE(Font::FirstAvailableOrFirst(std::string()).empty());
+
+  EXPECT_EQ("Arial", Font::FirstAvailableOrFirst("Arial"));
+  EXPECT_EQ("not exist", Font::FirstAvailableOrFirst("not exist"));
+
+  EXPECT_EQ("Arial", Font::FirstAvailableOrFirst("Arial, not exist"));
+  EXPECT_EQ("Arial", Font::FirstAvailableOrFirst("not exist, Arial"));
+  EXPECT_EQ("Arial",
+            Font::FirstAvailableOrFirst("not exist, Arial, not exist"));
+
+  EXPECT_EQ("not exist", Font::FirstAvailableOrFirst("not exist, not exist 2"));
+
+  EXPECT_EQ("Arial", Font::FirstAvailableOrFirst(", not exist, Arial"));
+  EXPECT_EQ("not exist", Font::FirstAvailableOrFirst(", not exist, not exist"));
+}
+
 }  // namespace
 }  // namespace gfx