C++ readability change for cindylau.

BUG=none
TEST=none
Review URL: http://codereview.chromium.org/2090008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@48733 0039d316-1c4b-4281-b951-d872f2087c98
 bool MatchFilter::MatchesString(const wchar_t* key, const std::string& value) {
  if (!details_->HasKey(key))
    return true;
  std::string filter_value;
  return (details_->GetString(key, &filter_value) &&
          value == filter_value);
}

 bool MatchFilter::MatchesString(const wchar_t* key, const std::string& value) {
  if (!details_->HasKey(key))
    return true;
  std::string filter_value;
  return (details_->GetString(key, &filter_value) &&
          value == filter_value);
}
