[Offline pages] Moving disk size related calls to Archive Manager, reorganizing UMA

components/offline_pages/archive_manager.h

 // Copyright 2016 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_OFFLINE_PAGES_ARCHIVE_MANAGER_H_
 #define COMPONENTS_OFFLINE_PAGES_ARCHIVE_MANAGER_H_
 
 #include <set>
 #include <vector>
 
 #include "base/callback_forward.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 
 namespace base {
 class SequencedTaskRunner;
 }  // namespace base
 
 namespace offline_pages {
 
 // Class that manages all archive files for offline pages. They are all stored
 // in a specific archive directory.
 // All tasks are performed using |task_runner_|.
 class ArchiveManager {
  public:
+  struct StorageStats {
+    int64_t free_disk_space;
+    int64_t total_archives_size;
+  };
+
   ArchiveManager(const base::FilePath& archives_dir,
                  const scoped_refptr<base::SequencedTaskRunner>& task_runner);
   virtual ~ArchiveManager();
 
   // Creates archives directory if one does not exist yet;
   virtual void EnsureArchivesDirCreated(const base::Closure& callback);
 
   // Checks whether an archive with specified |archive_path| exists.
   virtual void ExistsArchive(const base::FilePath& archive_path,
                              const base::Callback<void(bool)>& callback);
 
   // Deletes an archive with specified |archive_path|.
   // It is considered successful to attempt to delete a file that does not
   // exist.
   virtual void DeleteArchive(const base::FilePath& archive_path,
                              const base::Callback<void(bool)>& callback);
 
   // Deletes multiple archives that are specified in |archive_paths|.
   // It is considered successful to attempt to delete a file that does not
   // exist.
   virtual void DeleteMultipleArchives(
       const std::vector<base::FilePath>& archive_paths,
       const base::Callback<void(bool)>& callback);
 
   // Lists all archive files in the archive directory.
   virtual void GetAllArchives(
       const base::Callback<void(const std::set<base::FilePath>&)>& callback)
       const;
 
+  // Gets stats about archive storage, i.e. total archive sizes and free disk
+  // space.
+  virtual void GetStorageStats(
+      const base::Callback<void(const StorageStats& storage_sizes)>& callback)
+      const;
+
  private:
   // Path under which all of the managed archives should be stored.
   base::FilePath archives_dir_;
   // Task runner for running file operations.
   scoped_refptr<base::SequencedTaskRunner> task_runner_;
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_ARCHIVE_MANAGER_H_