Refactor CryptAuth component to be more testable.

components/proximity_auth/cryptauth/cryptauth_client_factory.h

 // Copyright 2015 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 COMPONENTS_PROXIMITY_AUTH_CRYPT_AUTH_CLIENT_FACTORY_H
 #define COMPONENTS_PROXIMITY_AUTH_CRYPT_AUTH_CLIENT_FACTORY_H
 
-#include "base/macros.h"
-#include "base/memory/weak_ptr.h"
-#include "components/proximity_auth/cryptauth/cryptauth_client.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
 #include "components/proximity_auth/cryptauth/proto/cryptauth_api.pb.h"
-#include "google_apis/gaia/oauth2_token_service.h"
-#include "net/url_request/url_request_context_getter.h"
+
+class OAuth2TokenService;
+
+namespace net {
+class URLRequestContextGetter;
+}
 
 namespace proximity_auth {
 
 class CryptAuthClient;
 
-// Factory for creating CryptAuthClient instances. Because each CryptAuthClient
-// instance can only be used for one API call, this class helps making multiple
-// requests in sequence or parallel easier.
+// Interface for creating CryptAuthClient instances. Because each
+// CryptAuthClient instance can only be used for one API call, a factory helps
+// making multiple requests in sequence or parallel easier.

[Ilya Sherman, 2015/04/06 18:53:33]

I don't see the advantage of creating an interface that's distinct from the
implementation.  What's the motivation here?

[Tim Song, 2015/04/06 23:21:17]

Discussed in person.

 class CryptAuthClientFactory {
  public:
-  // Creates the factory.
+  virtual ~CryptAuthClientFactory() {}
+
+  virtual scoped_ptr<CryptAuthClient> CreateInstance() = 0;

[Ilya Sherman, 2015/04/06 18:53:34]

Why did you make this virtual?

[Tim Song, 2015/04/06 23:21:17]

Discussed in person.

+
+  // Creates a default CryptAuthClientFactory.
   // |token_service|: Gets the user's access token.
   //     Needs to outlive this object.
   // |account_id|: The account id of the user.
   // |url_request_context|: The request context to make the HTTP requests.
   // |device_classifier|: Contains basic device information of the client.
-  CryptAuthClientFactory(
+  static scoped_ptr<CryptAuthClientFactory> CreateDefault(
       OAuth2TokenService* token_service,
       const std::string& account_id,
       scoped_refptr<net::URLRequestContextGetter> url_request_context,
       const cryptauth::DeviceClassifier& device_classifier);
-  virtual ~CryptAuthClientFactory();
-
-  // Creates and returns a CryptAuthClient instance that is owned by the caller.
-  scoped_ptr<CryptAuthClient> CreateInstance();
-
- private:
-  OAuth2TokenService* token_service_;
-  const std::string account_id_;
-  const scoped_refptr<net::URLRequestContextGetter> url_request_context_;
-  const cryptauth::DeviceClassifier device_classifier_;
-
-  DISALLOW_COPY_AND_ASSIGN(CryptAuthClientFactory);
 };
 
 }  // namespace proximity_auth
 
 #endif  // COMPONENTS_PROXIMITY_AUTH_CRYPT_AUTH_CLIENT_FACTORY_H