Cleanup: Convert ASCIIToUTF16("") to string16().

ui/gfx/font_unittest.cc

 // Copyright (c) 2011 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/string16.h"
 #include "base/utf_string_conversions.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
 #include <pango/pango.h>
 #elif defined(OS_WIN)
 #include "ui/gfx/platform_font_win.h"
 #endif
 
 namespace {
@@ skipping 79 matching lines @@
   ASSERT_GT(cf.GetExpectedTextWidth(3), cf.GetExpectedTextWidth(2));
 }
 
 TEST_F(FontTest, AvgCharWidth) {
   Font cf("Arial", 16);
   ASSERT_GT(cf.GetAverageCharacterWidth(), 0);
 }
 
 TEST_F(FontTest, Widths) {
   Font cf("Arial", 16);
-  ASSERT_EQ(cf.GetStringWidth(ASCIIToUTF16("")), 0);
+  ASSERT_EQ(cf.GetStringWidth(string16()), 0);
   ASSERT_GT(cf.GetStringWidth(ASCIIToUTF16("a")),
-            cf.GetStringWidth(ASCIIToUTF16("")));
+            cf.GetStringWidth(string16()));
   ASSERT_GT(cf.GetStringWidth(ASCIIToUTF16("ab")),
             cf.GetStringWidth(ASCIIToUTF16("a")));
   ASSERT_GT(cf.GetStringWidth(ASCIIToUTF16("abc")),
             cf.GetStringWidth(ASCIIToUTF16("ab")));
 }
 
 #if defined(OS_WIN)
 TEST_F(FontTest, DeriveFontResizesIfSizeTooSmall) {
   Font cf("Arial", 8);
   // The minimum font size is set to 5 in browser_main.cc.
   ScopedMinimumFontSizeCallback minimum_size(5);
 
   Font derived_font = cf.DeriveFont(-4);
   EXPECT_EQ(5, derived_font.GetFontSize());
 }
 
 TEST_F(FontTest, DeriveFontKeepsOriginalSizeIfHeightOk) {
   Font cf("Arial", 8);
   // The minimum font size is set to 5 in browser_main.cc.
   ScopedMinimumFontSizeCallback minimum_size(5);
 
   Font derived_font = cf.DeriveFont(-2);
   EXPECT_EQ(6, derived_font.GetFontSize());
 }
 #endif  // defined(OS_WIN)
 
 }  // namespace