Make UTF8ToWide take a StringPiece, to avoid copying to a std::string.

Make UTF8ToWide take a StringPiece, to avoid copying to a std::string.

The previous prototype took only a std::string, unless you used the less convenient output parameter version.  This required copying char* input to a std::string.  Using a StringPiece the input will be implicitly both std::string and char* without any copying.  This helps especially on Linux, where all input we get will be in utf8 char*.

[Dean McNamee, 2009-03-04 11:30:33]

If this goes well, I'd like to do it even more places (after some research on
the important ones).  Maybe there would even be a String16Piece some day.

[darin (slow to review), 2009-03-04 16:33:23]

LGTM

http://codereview.chromium.org/40106/diff/1/2
File base/string_util.h (right):

http://codereview.chromium.org/40106/diff/1/2#newcode185
Line 185: string16 UTF8ToUTF16(const std::string& utf8);
this looks like another good place to use this.

it'd be great too if we had a String16Piece :)