Introduce CryptAuthClient, a class capable of performing all CryptAuth APIs.

components/proximity_auth/cryptauth/cryptauth_api_call_flow.h

 // Copyright 2014 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_CRYPTAUTH_API_CALL_FLOW_H
 #define COMPONENTS_PROXIMITY_AUTH_CRYPTAUTH_API_CALL_FLOW_H
 
 #include <string>
 
 #include "base/callback.h"
@@ skipping 14 matching lines @@
   CryptAuthApiCallFlow(const GURL& request_url);
   ~CryptAuthApiCallFlow() override;
 
   // Starts the API call.
   //   context: The URL context used to make the request.
   //   access_token: The access token for whom to make the to make the request.
   //   serialized_request: A serialized proto containing the request data.
   //   result_callback: Called when the flow completes successfully with a
   //       serialized response proto.
   //   error_callback: Called when the flow completes with an error.
-  void Start(net::URLRequestContextGetter* context,
-             const std::string& access_token,
-             const std::string& serialized_request,
-             ResultCallback result_callback,
-             ErrorCallback error_callback);
+  virtual void Start(net::URLRequestContextGetter* context,
+                     const std::string& access_token,
+                     const std::string& serialized_request,
+                     const ResultCallback& result_callback,
+                     const ErrorCallback& error_callback);
 
  protected:
   // Reduce the visibility of OAuth2ApiCallFlow::Start() to avoid exposing
   // overloaded methods.
   using OAuth2ApiCallFlow::Start;
 
   // google_apis::OAuth2ApiCallFlow:
   GURL CreateApiCallUrl() override;
   std::string CreateApiCallBody() override;
   std::string CreateApiCallBodyContentType() override;
@@ skipping 13 matching lines @@
 
   // Callback invoked with an error message when the flow fails.
   ErrorCallback error_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(CryptAuthApiCallFlow);
 };
 
 }  // namespace proximity_auth
 
 #endif  // COMPONENTS_PROXIMITY_AUTH_CRYPTAUTH_API_CALL_FLOW_H