return early from ProcessRawBytesWithSeperators() when data length is 0

BUG=109717
TEST=N/A
Review URL: http://codereview.chromium.org/9169028

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@117241 0039d316-1c4b-4281-b951-d872f2087c98
std::string ProcessRawBytes(const unsigned char* data, size_t data_length) {
  return ProcessRawBytesWithSeparators(data, data_length, ' ', '\n');
}

std::string ProcessRawBytes(const unsigned char* data, size_t data_length) {
  return ProcessRawBytesWithSeparators(data, data_length, ' ', '\n');
}
