Clean up Cloud Print API flow code.

chrome/browser/printing/cloud_print/cloud_print_printer_list.h

 // Copyright 2013 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 CHROME_BROWSER_PRINTING_CLOUD_PRINT_CLOUD_PRINT_PRINTER_LIST_H_
 #define CHROME_BROWSER_PRINTING_CLOUD_PRINT_CLOUD_PRINT_PRINTER_LIST_H_
 
 #include <string>
 #include <vector>
 
 #include "base/values.h"
 #include "chrome/browser/printing/cloud_print/gcd_api_flow.h"
 
 namespace cloud_print {
 
 class CloudPrintPrinterList : public CloudPrintApiFlowRequest {
  public:
   struct Device {
-    Device();
-    ~Device();
-
     std::string id;
     std::string display_name;
     std::string description;
   };
-  typedef std::vector<Device> DeviceList;
+  using DeviceList = std::vector<Device>;
 
   class Delegate {
    public:
     Delegate();
     virtual ~Delegate();
 
     virtual void OnDeviceListReady(const DeviceList& devices) = 0;
     virtual void OnDeviceListUnavailable() = 0;
   };
 
   explicit CloudPrintPrinterList(Delegate* delegate);
   ~CloudPrintPrinterList() override;
 
+  // CloudPrintApiFlowRequest implementation:
   void OnGCDApiFlowError(GCDApiFlow::Status status) override;
-
   void OnGCDApiFlowComplete(const base::DictionaryValue& value) override;
-
   GURL GetURL() override;
 
  private:
   bool FillPrinterDetails(const base::DictionaryValue& printer_value,
                           Device* printer_details);
 
-  Delegate* delegate_;
+  Delegate* const delegate_;
 };
 
 }  // namespace cloud_print
 
 #endif  // CHROME_BROWSER_PRINTING_CLOUD_PRINT_CLOUD_PRINT_PRINTER_LIST_H_