Coverity: Fixing pass by value.
CID=101462, 101458, 101437, 101471, 101467

BUG=NONE
TEST=NONE

Review URL: http://codereview.chromium.org/9006023

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@115257 0039d316-1c4b-4281-b951-d872f2087c98
bool ExtensionPrefs::ReadExtensionPrefString(
    const std::string& extension_id, const std::string& pref_key,
    std::string* out_value) const {
  const DictionaryValue* ext = GetExtensionPref(extension_id);

  if (!ext || !ext->GetString(pref_key, out_value))
    return false;

  return true;
}

bool ExtensionPrefs::ReadExtensionPrefString(
    const std::string& extension_id, const std::string& pref_key,
    std::string* out_value) const {
  const DictionaryValue* ext = GetExtensionPref(extension_id);

  if (!ext || !ext->GetString(pref_key, out_value))
    return false;

  return true;
}
