Validate that paths don't contain embedded NULLs at deserialization.

BUG=166867

Review URL: https://chromiumcodereview.appspot.com/11743009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@174935 0039d316-1c4b-4281-b951-d872f2087c98
void ParamTraits<bool>::Log(const param_type& p, std::string* l) {
  l->append(p ? "true" : "false");
}

void ParamTraits<bool>::Log(const param_type& p, std::string* l) {
  l->append(p ? "true" : "false");
}
