[Payments] Code Refactoring for the Subkey Request

components/payments/core/subkey_requester.h

+// Copyright 2017 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_PAYMENTS_CORE_SUBKEY_REQUESTER_H_
+#define COMPONENTS_PAYMENTS_CORE_SUBKEY_REQUESTER_H_
+
+#include "base/macros.h"
+#include "third_party/libaddressinput/chromium/chrome_address_validator.h"
+
+namespace payments {
+
+using SubKeyReceiverCallback =
+    base::OnceCallback<void(const std::vector<std::string>&)>;
+
+// SubKeyRequester Loads Rules from the server and extracts the subkeys.
+// For a given key (region code for a country, such as US), the list of its
+// corresponding subkeys is the list of that countries admin areas (states,
+// provinces, ..).
+class SubKeyRequester : public autofill::LoadRulesListener {
+ public:
+  // The interface for the subkey request.
+  class Request {
+   public:
+    virtual void OnRulesLoaded() = 0;
+    virtual ~Request() {}
+  };
+
+  SubKeyRequester(std::unique_ptr<i18n::addressinput::Source> source,
+                  std::unique_ptr<i18n::addressinput::Storage> storage);
+  ~SubKeyRequester() override;
+
+  // If the rules for |region_code| are loaded, this gets the subkeys for the
+  // |region_code|,  synchronously. If they are not loaded yet, it sets up a
+  // task to get the subkeys when the rules are loaded (asynchronous). If the
+  // loading has not yet started, it will also start loading the rules for the
+  // |region_code|. The received subkeys will be returned to the |requester|. If
+  // the subkeys are not received in |timeout_seconds|, then the requester will
+  // be informed and the request will be canceled. |requester| should never be
+  // null.
+  void StartRegionSubKeysRequest(const std::string& region_code,
+                                 int timeout_seconds,
+                                 SubKeyReceiverCallback cb);
+
+  // Returns whether the rules for the specified |region_code| have finished
+  // loading.
+  bool AreRulesLoadedForRegion(const std::string& region_code);
+
+  // Start loading the rules for the specified |region_code|.
+  virtual void LoadRulesForRegion(const std::string& region_code);
+
+  // Cancels the pending subkey request task.
+  void CancelPendingGetSubKeys();
+
+ private:
+  // Called when the address rules for the |region_code| have finished
+  // loading. Implementation of the LoadRulesListener interface.
+  void OnAddressValidationRulesLoaded(const std::string& region_code,
+                                      bool success) override;
+
+  // The region code and the request for the pending subkey request.
+  std::unique_ptr<Request> pending_subkey_request_;
+  std::string pending_subkey_region_code_;
+
+  // The address validator used to load subkeys.
+  autofill::AddressValidator address_validator_;
+
+  DISALLOW_COPY_AND_ASSIGN(SubKeyRequester);
+};
+
+}  // namespace payments
+
+#endif  // COMPONENTS_PAYMENTS_CORE_SUBKEY_REQUESTER_H_