Move UTF16ToASCII, remove WideToASCII.

base/strings/utf_string_conversions.cc

 // Copyright (c) 2010 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/strings/utf_string_conversions.h"
 
 #include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversion_utils.h"
 
@@ skipping 164 matching lines @@
 std::wstring ASCIIToWide(const StringPiece& ascii) {
   DCHECK(IsStringASCII(ascii)) << ascii;
   return std::wstring(ascii.begin(), ascii.end());
 }
 
 string16 ASCIIToUTF16(const StringPiece& ascii) {
   DCHECK(IsStringASCII(ascii)) << ascii;
   return string16(ascii.begin(), ascii.end());
 }
 
+std::string UTF16ToASCII(const string16& utf16) {
+  DCHECK(IsStringASCII(utf16)) << UTF16ToUTF8(utf16);
+  return std::string(utf16.begin(), utf16.end());
+}
+
 }  // namespace base