Cleanup return values in http_auth

net/http/http_auth_cache.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_HTTP_HTTP_AUTH_CACHE_H_
 #define NET_HTTP_HTTP_AUTH_CACHE_H_
 
 #include <list>
 #include <string>
 
@@ skipping 18 matching lines @@
  public:
   class NET_EXPORT_PRIVATE Entry {
    public:
     ~Entry();
 
     const GURL& origin() const {
       return origin_;
     }
 
     // The case-sensitive realm string of the challenge.
-    const std::string realm() const {
-      return realm_;
-    }
+    const std::string& realm() const { return realm_; }
 
     // The authentication scheme of the challenge.
     HttpAuth::Scheme scheme() const {
       return scheme_;
     }
 
     // The authentication challenge.
-    const std::string auth_challenge() const {
-      return auth_challenge_;
-    }
+    const std::string& auth_challenge() const { return auth_challenge_; }
 
     // The login credentials.
     const AuthCredentials& credentials() const {
       return credentials_;
     }
 
     int IncrementNonceCount() {
       return ++nonce_count_;
     }
 
@@ skipping 119 matching lines @@
 
  private:
   typedef std::list<Entry> EntryList;
   EntryList entries_;
 };
 
 // An authentication realm entry.
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_AUTH_CACHE_H_