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

chrome/browser/autofill/form_field_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 "base/string16.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/autofill/autofill_field.h"
 #include "chrome/browser/autofill/form_field.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 TEST(FormFieldTest, Match) {
   AutofillField field;
 
   // Empty strings match.
   EXPECT_TRUE(FormField::Match(&field, string16(), FormField::MATCH_LABEL));
 
   // Empty pattern matches non-empty string.
   field.label = ASCIIToUTF16("a");
   EXPECT_TRUE(FormField::Match(&field, string16(), FormField::MATCH_LABEL));
 
   // Strictly empty pattern matches empty string.
-  field.label = ASCIIToUTF16("");
+  field.label = string16();
   EXPECT_TRUE(FormField::Match(&field, ASCIIToUTF16("^$"),
               FormField::MATCH_LABEL));
 
   // Strictly empty pattern does not match non-empty string.
   field.label = ASCIIToUTF16("a");
   EXPECT_FALSE(FormField::Match(&field, ASCIIToUTF16("^$"),
                FormField::MATCH_LABEL));
 
   // Non-empty pattern doesn't match empty string.
   field.label = string16();
@@ skipping 74 matching lines @@
   field.label = ASCIIToUTF16("contains word:");
   EXPECT_TRUE(FormField::Match(&field, ASCIIToUTF16("\\bword\\b"),
                                FormField::MATCH_LABEL));
   EXPECT_FALSE(FormField::Match(&field, ASCIIToUTF16("\\bcon\\b"),
                                 FormField::MATCH_LABEL));
   // Make sure the circumflex in 'crepe' is not treated as a word boundary.
   field.label = UTF8ToUTF16("cr" "\xC3\xAA" "pe");
   EXPECT_FALSE(FormField::Match(&field, ASCIIToUTF16("\\bcr\\b"),
                                 FormField::MATCH_LABEL));
 }