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

ui/gfx/font_list_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_list.h"
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
@@ skipping 338 matching lines @@
   EXPECT_LT(derived_1.GetFontSize(), font_list.GetFontSize());
 
   // A larger upper bound should not change the height of the font list.
   const int height_2 = font_list.GetHeight() + 5;
   FontList derived_2 = font_list.DeriveWithHeightUpperBound(height_2);
   EXPECT_LE(derived_2.GetHeight(), height_2);
   EXPECT_EQ(font_list.GetHeight(), derived_2.GetHeight());
   EXPECT_EQ(font_list.GetFontSize(), derived_2.GetFontSize());
 }
 
+TEST(FontListTest, FirstAvailableOrFirst) {
+  EXPECT_TRUE(FontList::FirstAvailableOrFirst("").empty());
+  EXPECT_TRUE(FontList::FirstAvailableOrFirst(std::string()).empty());
+
+  EXPECT_EQ("Arial", FontList::FirstAvailableOrFirst("Arial"));
+  EXPECT_EQ("not exist", FontList::FirstAvailableOrFirst("not exist"));
+
+  EXPECT_EQ("Arial", FontList::FirstAvailableOrFirst("Arial, not exist"));
+  EXPECT_EQ("Arial", FontList::FirstAvailableOrFirst("not exist, Arial"));
+  EXPECT_EQ("Arial",
+            FontList::FirstAvailableOrFirst("not exist, Arial, not exist"));
+
+  EXPECT_EQ("not exist",
+            FontList::FirstAvailableOrFirst("not exist, not exist 2"));
+
+  EXPECT_EQ("Arial", FontList::FirstAvailableOrFirst(", not exist, Arial"));
+  EXPECT_EQ("not exist",
+            FontList::FirstAvailableOrFirst(", not exist, not exist"));
+}
+
 }  // namespace gfx