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

ui/gfx/font_unittest.cc

Index: ui/gfx/font_unittest.cc
diff --git a/ui/gfx/font_unittest.cc b/ui/gfx/font_unittest.cc
index e123d96794ea7021bf27332d8dca9d15dc436969..6200064e2bd5b10eb2dfc428b50c15f58a115bd7 100644
--- a/ui/gfx/font_unittest.cc
+++ b/ui/gfx/font_unittest.cc
@@ -195,5 +195,23 @@ TEST_F(FontTest, DeriveKeepsOriginalSizeIfHeightOk) {
 }
 #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