Add UTF16ToUTF8AndAdjustOffset() to base/.

base/utf_offset_string_conversions.h

 // 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.
 
 #ifndef BASE_UTF_OFFSET_STRING_CONVERSIONS_H_
 #define BASE_UTF_OFFSET_STRING_CONVERSIONS_H_
 #pragma once
 
 #include <string>
 #include <vector>
 
 #include "base/base_export.h"
 #include "base/string16.h"
 
 namespace base {
 class StringPiece;
+class StringPiece16;
 }
 
 // Like the conversions in utf_string_conversions.h, but also takes one or more
 // offsets (|offset[s]_for_adjustment|) into the source strings, each offset
 // will be adjusted to point at the same logical place in the result strings.
 // If this isn't possible because an offset points past the end of the source
 // strings or into the middle of a multibyte sequence, the offending offset will
 // be set to string16::npos. |offset[s]_for_adjustment| may be NULL.
 BASE_EXPORT bool UTF8ToUTF16AndAdjustOffset(const char* src,
                                             size_t src_len,
                                             string16* output,
                                             size_t* offset_for_adjustment);
 BASE_EXPORT bool UTF8ToUTF16AndAdjustOffsets(
     const char* src,
     size_t src_len,
     string16* output,
     std::vector<size_t>* offsets_for_adjustment);
 
 BASE_EXPORT string16 UTF8ToUTF16AndAdjustOffset(const base::StringPiece& utf8,
                                                 size_t* offset_for_adjustment);
 BASE_EXPORT string16 UTF8ToUTF16AndAdjustOffsets(
     const base::StringPiece& utf8,
     std::vector<size_t>* offsets_for_adjustment);
 
+BASE_EXPORT std::string UTF16ToUTF8AndAdjustOffset(
+    const base::StringPiece16& utf16,
+    size_t* offset_for_adjustment);
+BASE_EXPORT std::string UTF16ToUTF8AndAdjustOffsets(
+    const base::StringPiece16& utf16,
+    std::vector<size_t>* offsets_for_adjustment);
+
 // Limiting function callable by std::for_each which will replace any value
 // which is equal to or greater than |limit| with npos.
 template <typename T>
 struct LimitOffset {
   explicit LimitOffset(size_t limit)
     : limit_(limit) {}
 
   void operator()(size_t& offset) {
     if (offset >= limit_)
       offset = T::npos;
@@ skipping 26 matching lines @@
   void Add(const Adjustment& adjustment);
 
  private:
   void AdjustOffset(std::vector<size_t>::iterator offset);
 
   std::vector<size_t>* offsets_for_adjustment_;
   std::vector<Adjustment> adjustments_;
 };
 
 #endif  // BASE_UTF_OFFSET_STRING_CONVERSIONS_H_