Change UTF8ToUTF16 to accept const StringPiece&.

base/utf_string_conversions.h

 // Copyright (c) 2009 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_STRING_CONVERSIONS_H_
 #define BASE_UTF_STRING_CONVERSIONS_H_
 #pragma once
 
 #include <string>
 
 #include "base/string16.h"
-
-namespace base {
-class StringPiece;
-}
+#include "base/string_piece.h"

[Avi (use Gerrit), 2011/01/26 21:58:55]

Why? We don't need it for the declaration in this file. Anyone who includes this
file and uses UTF8ToUTF16 should include it there. See the comment starting on
line 51 in this file.

[James Su, 2011/01/26 22:13:30]

But from string_piece.h:

// Functions or methods may use const StringPiece& parameters to accept either
// a "const char*" or a "string" value that will be implicitly converted to
// a StringPiece.  The implicit conversion means that it is often appropriate
// to include this .h file in other files rather than forward-declaring
// StringPiece as would be appropriate for most other Google classes.


And I think the users of UTF8ToUTF16() shouldn't care about the existence of
StringPiece at all, it would be strange for them to include string_piece.h in
order to use UTF8ToUTF16.

 
 // These convert between UTF-8, -16, and -32 strings. They are potentially slow,
 // so avoid unnecessary conversions. The low-level versions return a boolean
 // indicating whether the conversion was 100% valid. In this case, it will still
 // do the best it can and put the result in the output buffer. The versions that
 // return strings ignore this error and just return the best conversion
 // possible.
 bool WideToUTF8(const wchar_t* src, size_t src_len, std::string* output);
 std::string WideToUTF8(const std::wstring& wide);
 bool UTF8ToWide(const char* src, size_t src_len, std::wstring* output);
 std::wstring UTF8ToWide(const base::StringPiece& utf8);
 
 bool WideToUTF16(const wchar_t* src, size_t src_len, string16* output);
 string16 WideToUTF16(const std::wstring& wide);
 bool UTF16ToWide(const char16* src, size_t src_len, std::wstring* output);
 std::wstring UTF16ToWide(const string16& utf16);
 
 bool UTF8ToUTF16(const char* src, size_t src_len, string16* output);
-string16 UTF8ToUTF16(const std::string& utf8);
+string16 UTF8ToUTF16(const base::StringPiece& utf8);
 bool UTF16ToUTF8(const char16* src, size_t src_len, std::string* output);
 std::string UTF16ToUTF8(const string16& utf16);
 
 // We are trying to get rid of wstring as much as possible, but it's too big
 // a mess to do it all at once.  These conversions should be used when we
 // really should just be passing a string16 around, but we haven't finished
 // porting whatever module uses wstring and the conversion is being used as a
 // stopcock.  This makes it easy to grep for the ones that should be removed.
 #if defined(OS_WIN)
 # define WideToUTF16Hack
@@ skipping 11 matching lines @@
 // forward declare it and force all callers to include string_piece.h. Given
 // that string_piece brings in complicated stuff like <algorithm>, it's
 // easier to just duplicate these very simple definitions for the two calling
 // cases we actually use.
 std::wstring ASCIIToWide(const char* ascii);
 std::wstring ASCIIToWide(const std::string& ascii);
 string16 ASCIIToUTF16(const char* ascii);
 string16 ASCIIToUTF16(const std::string& ascii);
 
 #endif  // BASE_UTF_STRING_CONVERSIONS_H_