Make ClearBrowsingDataHandler only observe its own removal task

chrome/browser/ui/webui/settings/settings_clear_browsing_data_handler.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 CHROME_BROWSER_UI_WEBUI_SETTINGS_SETTINGS_CLEAR_BROWSING_DATA_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_SETTINGS_SETTINGS_CLEAR_BROWSING_DATA_HANDLER_H_
 
 #include <memory>
 #include <string>
 #include <vector>
@@ skipping 12 matching lines @@
 }
 
 namespace content {
 class WebUI;
 }
 
 namespace settings {
 
 // Chrome browser startup settings handler.
 class ClearBrowsingDataHandler : public SettingsPageUIHandler,
-                                 public BrowsingDataRemover::Observer,
                                  public sync_driver::SyncServiceObserver {
  public:
   explicit ClearBrowsingDataHandler(content::WebUI* webui);
   ~ClearBrowsingDataHandler() override;
 
   // WebUIMessageHandler implementation.
   void RegisterMessages() override;
   void OnJavascriptAllowed() override;
   void OnJavascriptDisallowed() override;
 
  private:
+  // Observes one |remover| task initiated from ClearBrowsingDataHandler.
+  // Calls |callback| when the task is finished.
+  class TaskObserver;
+
   // Clears browsing data, called by Javascript.
   void HandleClearBrowsingData(const base::ListValue* value);
 
-  // BrowsingDataRemover::Observer implementation.
-  void OnBrowsingDataRemoving(bool is_removing) override;
+  // Called when a clearing task finished. |webui_callback_id| is provided
+  // by the WebUI action that initiated it.
+  void OnClearingTaskFinished(const std::string& webui_callback_id);
 
   // Updates UI when the pref to allow clearing history changes.
   virtual void OnBrowsingHistoryPrefChanged();
 
   // Initializes the dialog UI. Called by JavaScript when the DOM is ready.
   void HandleInitialize(const base::ListValue* args);
 
   // Implementation of SyncServiceObserver. Updates the footer of the dialog
   // when the sync state changes.
   void OnStateChanged() override;
@@ skipping 17 matching lines @@
   // Updates a counter text according to the |result|.
   void UpdateCounterText(
       std::unique_ptr<browsing_data::BrowsingDataCounter::Result> result);
 
   // Cached profile corresponding to the WebUI of this handler.
   Profile* profile_;
 
   // Counters that calculate the data volume for individual data types.
   std::vector<std::unique_ptr<browsing_data::BrowsingDataCounter>> counters_;
 
+  // Observes the currently active data clearing task.
+  std::unique_ptr<TaskObserver> task_observer_;
+
   // ProfileSyncService to observe sync state changes.
   ProfileSyncService* sync_service_;
   ScopedObserver<ProfileSyncService, sync_driver::SyncServiceObserver>
       sync_service_observer_;
 
-  // Observe the remover progress.
-  BrowsingDataRemover* remover_;
-  ScopedObserver<BrowsingDataRemover, BrowsingDataRemover::Observer>
-      remover_observer_;
-
-  // The WebUI callback ID of the last performClearBrowserData request. There
-  // can only be one such request in-flight.
-  std::string webui_callback_id_;
-
   // Used to listen for pref changes to allow / disallow deleting browsing data.
   PrefChangeRegistrar profile_pref_registrar_;
 
   // Whether the sentence about other forms of history stored in user's account
   // should be displayed in the footer. This value is retrieved asynchronously,
   // so we cache it here.
   bool show_history_footer_;
 
   // Whether we should show a dialog informing the user about other forms of
   // history stored in their account after the history deletion is finished.
   bool show_history_deletion_dialog_;
 
   // A weak pointer factory for asynchronous calls referencing this class.
   base::WeakPtrFactory<ClearBrowsingDataHandler> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ClearBrowsingDataHandler);
 };
 
 }  // namespace settings
 
 #endif  // CHROME_BROWSER_UI_WEBUI_SETTINGS_SETTINGS_CLEAR_BROWSING_DATA_HANDLER_H_